Talk:Boiling frog/sources

Overview 1800s sources re: Boiling frog. Copypaste of (hopefully) complete relevant texts where available, includes OCR errors. Facsimiles are available for more accuracy of texts hosted at archive.org. Feel free to correct or add sources, please leave any comments at Talk:Boiling frog.

Goltz (1869)
Goltz, F., (1869) Beitrage zur Lehre von den Functionen der Nervencentren des

Frosches, Berlin.

http://books.google.com/books?id=YzsAAAAAQAAJ&ots=iOwABXAL10 (Full text in German)

Heinzmann (1872)
Heinzmann, A. (1872) “Ueber die Wirkung Sehr Allmäliger Aenderungen Thermischer

Reize auf die Empfindungsnerven, Archiv fur die Gesammte Physiologie, Bd. VI,

222-236.

http://www.springerlink.com/content/w3n77m1m5732474t/ (German, behind paywall)

Foster (1873)
Foster, M.A. (1873), “On the Effects of a Gradual Rise of Temperature on Reflex Actions

in the Frog”, Journal of Anatomy and Physiology, viii, 45-53.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1319000/pdf/janatphys00201-0052.pdf (English, full text)

Fratscher (1875)
Fratscher, C. (1875), “Ueber Continuirliche und Langsame Nervenreizung”, Jenaische

Zeitschrift, N. F. I 1, 130.

http://books.google.com/books?id=4eUAAAAAYAAJ (German, only snippet view)

Sedgwick (1882)
Sedgwick, W.T. “On Variations of Reflex-Excitability in the Frog, Induced by Changes

in Temperature” 385-410 in Studies from the Biological Laboratory ed. Newell

Martin, Johns Hopkins University, Baltimore.

http://www.archive.org/details/studiesfrombiol00martgoog (English, full text)

http://www.archive.org/stream/studiesfrombiol00martgoog#page/n402/ (direct link to facsimile)


 * Google books has it now - I think their interface is a little nicer. http://books.google.com/books?id=-LcEAAAAQAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false Rsheridan6 (talk) 20:55, 9 January 2011 (UTC)

ON VARIATIONS OP REFLEX-EXCITABILITY IN THE FROG, INDUCED BY CHANGES OF TEMPERATURE. By W. T. SEDGWICK, Ph. D.

Physiologists aro by no means agreed as to the effects upon reflex actions of changes in temperature. It is generally admitted that a cool temperature is favorable either for preserving or working upon reflex preparations, and that a warm tempera- ture is equally unfavorable ; but beyond and between these general and indefinite ideas there is a wide difference of opinion both as to facts and causes. This is the more surprising because looked at & priori nothing should be simpler. The organs com- bined to make up a reflex apparatus though now, in the adult, physiologically and structurally unlike, have all directly descended from similar protoplasmic masses in the embryo. Their tissues are composed, even in their highly differentiated conditions, of protoplasm more or less modified, and they should, therefore, obey less or more closely those laws which govern protoplasmic activity.

Every one knows that protoplasm wherever found behaves very definitely in respect to temperature. From almost complete inactivity at a low temperature it passes, with a gradual rise of temperature, little by little into a phase of greatest activity, beyond which under excessive heat its functions fall rather quickly back to zero, or if the temperature be raised still higher, pass beyond and disappear with the occurrence of coagulation and death.

It is agreed that most of the tissues and organs of the frog, taken separately, do obey the laws which govern their protoplas- mic basis. Muscles, afferent and efferent nerves, and glands exhibit nearly the same series of events which may be observed in an amoeba or in a white blood-corpuscle. Even the heart — by no means a simple protoplasmic organ — is subject to the same laws when free from nervous disturbances. One fact of extreme

385

386 W. T. SEDGWICK.

importance must not be overlooked. Various protoplasmic combinations exhibit their periods of greatest activity at very different degrees of temperature. In some cases it might be supposed, therefore, that one portion of an apparatus would, per- haps, pass beyond its own period of activity before some other part would have reached the temperature best suited to it, thus causing the apparatus as a whole to behave in a contradictory or exceptional manner. It must be granted, however, upon the theory of the correlation of parts that it would be ordinarily more advantageous to the organism to have come to possess organs made up of harmonious than of discordant tissues ; so that, unless evidence to the contrary is brought forward, we may reasonably expect to find in the parts of any apparatus no such dissimilarity in respect to their behavior toward changes of temperature.

It is within the experience of every physiologist that the frog, which, even in the normal state, is now admitted to be to a great extent a reflex mechanism, exhibits a noteworthy increase of functional activity as the temperature of winter gives way before that of summer. That the energetic movements wit- nessed in the summer, in the animal keenly alive to external stimuli, pass over in the autumn into the drowsy repose of the winter " sleep," is also known to every one. It is, therefore, somewhat surprising as well as confusing to read that in the brain- less frog (a much more perfect reflex apparatus than the normal one) the motor and sensory nerves, according to most authors, obey the laws of protoplasm, while others state that the spinal cord exactly reverses them ; to find that gentle heating of a reflex frog, in the opinion of one writer heightens the reflex excitability, and lowers it according to another; that packing of the body in ice increases enormously the reflex-excitability, and the same thing done with hot sand gives the same result ; that the spasms of strychnia poisoning, commonly supposed to indicate a high-grade excitability, and which have disap- peared in a room at the ordinary temperature, may be developed again in full force by laying the frog upon ice ; while we are told that in spite of the fact that thermal stimuli are powerful agents for exciting reflex movements, a brainless frog will sit motionless until boiled, in water whose temperature is gradually raised. A

TEMPERATURE AND REFLEX ACTIONS. 387

brief review of some of the literature of the subject will show that these apparent contradictions actually exist.

I. Historical.

Brown-Sequard l seems to have been one of the first to consider the effects of temperature upon reflex frogs. Having once suc- ceeded in June in keeping such an animal alive much longer than usual, he was led to observe again in September and later, and found at length that he could keep frogs, etc., in good condi- tion during these months for days and even weeks after the destruction of the medulla, while previously an hour or two was the longest time observed. He also noted the effects of destruc- tion of portions of the cord ; and when the objection was raised that very likely the prolonged vitality detected by him in the autumn was due only to the same actual amount of energy fading out more slowly (owing to the retardation of functional activity by the lower temperature), he replied by advancing experimental evidence that there is really more energy exhibited in the fall than in the summer — a more prolonged and vigorous vitality rather than a longer exhibition of an enfeebled vitality.

Kunde? writing a revised account of his previous work, states that if a frog be cooled, an electric current which, when the frog was warmer, produced tetanic movements, now either produces them later or not at all. He investigates the effects of temper- ature upon the spinal cord by giving frogs strychnia and then placing the animals in water at different temperatures. From his researches lie concludes that frogs under small doses of strych- nia, lose their spasms in the cold and regain them when brought back into a warm room. A dose just large enough to produce spasms in a warm room having been given, the animal was put upon ice and the spasms disappeared. If the animal were held in the hand of the observer or carried back into the warm room they returned. Large doses have precisely the opposite effect. The spasms in this case having dis- appeared under heat, will reappear in the cold. His work, then, indicates that cold depresses reflex excitability, except in severe strychnia poisoning.

1 For titles see list of references at the end of this paper.

388 W. T. SEDGWICK.

Cayradef writing in 1864, states that heat shortens the dura- tion of reflex movements, but increases their energy. When the increase of temperature is gradual, "as in nature," the reflex functions also increase gradually their functional activity ; " move- ments are more speedy, more energetic, and contractions last longer." When the temperature is " very high, 29°-30°, for example," section of the medulla produces tetanus and convul- sions; from which it appears that his conclusions given above are drawn, in part at least, from intact frogs.

He believes that a sudden rise of temperature is depressing in its effects upon the reflexes, an opinion derived from his considera- tion of Kunde's earlier work (1857), in which a frog poisoned to tetanus at the ordinary temperature, lost the spasms and re- covered at 34° : also from this observation ; if two cats of equal weight be poisoned with the same-sized doses of strychnia, and if, when tetanus has appeared, one be left in a room at the or- dinary temperature (16°-19° 0.) while the other i6 put in a room at 40° C, the former speedily dies, while the latter gradually re- covers. He closes the subject with the remark that in order to work upon frogs in the summer, one must keep them covered with wet linen, which keeps them both cool and moist.

Weir-Mitchell* and Richardson* published in 1867 communi- cations on the effects of extreme cold (freezing by ether and rhigolene spray) upon frogs and some other animals. Incident- ally they remark that the freezing, if not too sudden, was the cause of a preliminary stage of increased excitability, though this speedily passed into total loss of function, if the whole ani- mal were frozen, or if all of the cerebro spinal axis were affected. They observed that frogs and rabbits having frozen brains behaved in respect to their reflex actions precisely as if they had been decapitated, i. e, the reflex-excitability rose enormously.

For the purpose of demonstrating a striking difference between the normal and the brainless frog in respect to conscious sensa- tion, Goltz 6 in 1869 recalled an experiment described by him long before that time. Though employed by Goltz for a quite different purpose, it is nevertheless of great interest to us, since it has given rise to no small difference of opinion concerning the effects of heat upon reflex excitability. Goltz's experiment is as follows: A normal frog if immersed in water which is

TEMPERATURE AND REFLEX ACTIOSS. 389

gradually heated, speedily becomes violent in his attempts to escape. In striking contrast to this phenomenon is the behavior of the brainless frog, which, on the contrary, save for a few un- important twitches, sits motionless until it is dead from the ex- cessive heat. Though Goltz makes no definite statements as to the cause of this singular quiet of a highly excitable reflex frog (a matter which has been studied by Foster et #/.), it seem** fair to conclude from the context that he refers it to a dullness of perception which is not present in the frog possessing a cerebrum.

Tarckanow 7 studied in the first place the effects of heating and cooling sectional areas of the central nervous system. For this purpose he used either high or low temperatures (heated oil or ice) and thus applied powerful stimuli. His results indicate a marked coincidence between chemical or electrical and thermal stimuli. Besides, he devised the following important experi- ment :

" If the spinal cord of a decapitated frog be laid bare along its length and covered with ice or snow, a definite depression of the tactile reflexes will be noticed. If, on the other hand, the cooling take place upon the intact trunk of a frog similarly de- capitated and without any opening of the neural canal, we ob- tain results diametrically opposed to the foregoing, L e* a quite clearly pronounced increase of reflex excitability."

In order to effect this, he recommends that the trunk of the frog be packed in ice, by means of a bag or sack .having holes below for the hind legs.

Tarchanow has also studied upon the normal frog the effects of heating and cooling, and employed for the purpose, apparently not knowing of Goltz's work, the same method which was de- vised much earlier by that observer. He notes the period of unrest through which the animal passes as the temperature rises, and also the period of prostration which finally ensues. He calls attention to the fact that since the cause of this prostration can- not lie in the nerves or muscles (these being found intact), it must be sought in the brain or spinal cord. By certain experi- ments not wholly free from objection, he concludes that the cause lies in the brain and not in the spinal cord. He points out again that direct cooling, by ice or snow, of the exposed cord, as described above, gives a depression of excitability. Indirect

390 W. T. SEDGWICK.

cooling by ice-packing gives an enormous rise of that excitability, but he omits to explain this difference, as early in the paper he promises to do, and leaves it without further remark.

Heinzmann* working under the guidance of Preyer, published in the next year (1872) a paper of very great interest to the student of this subject. Starting from the fact that a motor nerve may be subjected to stimulation (chemical, electrical, pressure, and heat and cold stimuli are mentioned) too feeble to excite movement of the connected muscle, and that this stimulation may be gradually increased in intensity so far as to produce finally destruction of the nerve and yet without causing the least movement in the muscle, Heinzmann raises the question as to whether or not the same thing is true of sensory (afferent) nerves.

Thermal stimuli seemed to offer the best opportunity for the examination of this question, and by means of a carefully arranged apparatus the work was begun.

Normal frogs and frogs destitute of cerebral hemispheres were heated very gradually both " locally " and " totally." The local heating was by dipping one leg of a frog hung by the jaw from a hook, in water whose temperature could be gradually raised or lowered. In the " total stimulation " the whole body was heated by allowing the frog to sit upon cork floating in a cylinder of water which could be heated gradually. A uniform result was obtained.

The frog destitute of cerebral hemispheres could be heated easily, the normal frog for obvious reasons with some difficulty, until death ensued ; often passing from, perhaps, 22° C. to 40° or 45° ; or could be cooled as many degrees with a similar absence of movement. This result seemed to Heinzmann satisfactory. It put the sensory alongside the motor nerve in this respect, and seemed only to add another support to a well-established law. Heinzmann's conclusions in regard to the " total" heating of the normal frog must be compared with those of Goltz and Tarchanow, who both found, unlike Heinzmann, that gradual, heating of the normal frog produced most violent movements. Heinzmann does not refer to the work of either of these observers, and appar- ently does not know that in recording the quiet of the headless frog under a gradual rise of temperature he is but repeating a much earlier experiment of Goltz. It must not be overlooked

TEMPERATURE AND REFLEX ACTIONS. 391

that his explanation of the phenomenon differs widely from that which might be inferred from Goltz's paper. The latter's work seems to imply that the quiet of the brainless frog is due to dullness of perception, so to speak, while Heinzmann sees in the phenomenon a failure to secure movement due merely to a lack of stimuli succeeding each other with sufficient rapidity.

Heinzmann has also undertaken to fix the nearest tempera- tures at which reflexes appear in frogs of known warmth under heating or cooling of fixed rapidity (Reflex8chwelle\ and the rapidity of stimulation needful to provoke movement at various temperatures ( Unterschiedsschwelle).

In 1872 appeared in the Russian language a paper by Tarchanow* on the physiology of thermal reflexes. I have not seen the original, but have been obliged to depend for an abstract of it upon the Jahreshericht of Hofman and Schwalbe for 1872.

The author compared with each other the sensibility of the skin and afferent nerve, and concluded that special end-organs for, the detection of thermal stimuli must be located in the skin. Setschenow had already advanced the idea of special end-organs for the detection of chemical stimuli, and others have located there tactile end-organs, so that Tarchanow remarks that it only remains for* the microscope to detect the structural peculiarities of these three kinds of nervous end-organs. He has noticed the unrest of the frog destitute merely of the cere- bral hemispheres, already observed by Goltz long before. Finally, having observed that warm dilute acid (in Tiirck's method) called forth reflexes sooner than the same acid when cool, he proceeds to draw from the fact two interesting conclusions: 1. "This result can be explained by the hypothesis that by the higher temperature the irritability of the nerve-endings in the skin is increased." 2. "In this way, probably, is to be explained the well-known fact that on passing from a warm into a cooler me- dium the animal reacts more quickly than when passing from a cool into a warmer medium ; in the former case the end-organs are in a more irritable condition."

Dr. M. Foster, 10 in 1873, raised the question why, in the ex- periment of Goltz described above, the brainless frog (a far bet- ter reflex machine than the normal one) remains undisturbed in water the temperature of which is gradually raised. Goltz

392 W. T. SEDGWICK.

argues for a greater dullness of perception in the brainless frog, because it sits quiet under conditions which throw the normal frog into violent movements, viz. under a rising temperature ; but he does not mention that we have a strange anomaly in the fact that the normal frog, whose reflex functions are feebler than those of the decapitated animal, reacts much sooner upon the application of heat-stimuli. I shall shortly return to this paper, so that at present it need only be said that Dr. Foster, who apparently had not seen the paper of Heinzmann, published a year before, came to a result wholly different from that author. Heinzmann believes the quiet of the reflex frog to be due to a lack of stimuli-changes succeeding each other with sufficient sudden- ness ; Foster, on the contrary, believes the spinal cord to be directly depressed in function by the hot circulating blood.

In the same year (1873), appeared in the Russian language an article by Archangelshy^ 11 on the influence of warmth upon the nervous and blood-vascular systems of the frog. Of this paper I have seen only an abstract given in the Jahresbericht of Hofman and Schwalbe for 1S73. Archangelsky used in his work, as a convenient means of regulating the temperature, a wooden box having two windows, and provided inside with tubes arranged zigzag upon its walls, so that they presented a large surface to the air of the chamber and could be filled with hot or cold water at will. He seems to have worked first upon normal frogs ; and he found that when these were warmed to 29°-34° C, cramps were readily observed, succeeded by weakness, inaction and heat- rigor. He remarks that it is a matter of indifference whether the air be moist or dry, the end-result being the same. When it is moist, however, a high temperature is much sooner reached.

Upon decapitated frogs he has investigated according to Turck's method the variations of reflex-excitability. He does not say whether the air was dry or moist in this case. Under rapid heating he finds the excitability, at first, heightened ; under slow heating he was able to discover no change in the irritability at the outset. He finds " in many cases " that when the temperature has reached 25°-30° C. the reflexes evoked by acid become gradually weaker and finally cease, though the tactile reflexes remain some- what longer (33°-34°). The acid and the water for removing it from the foot were kept inside of the warm chamber.

TEMPERATURE AND REFLEX ACTIONS. 393

Archangelsky has also studied, in respect to its behavior toward warmth, the reflex apparatus analyzed into its separate parts ; having sought in this way to locate the cause of the failure of reflex power under heat.

(a) The end-organs. " It proved to be the fact that the higher the temperature of the acidified water, the sooner were the feet withdrawn. Hence the excitability of the end-organs is height- ened by heat."

(5) The afferent nerve. Like other observers, the author finds the afferent nerve to be more irritable when warmed ; he says, however, that slow warming has no perceptible effect.

(c) The spinal cord. Two needles having been thrust into the cord of a decapitated frog, were connected with an induction apparatus. As a measure of the excitability, that distance of the secondary from the primary coil which was just sufficient to pro- duce a minimal contraction of the muscles, was employed. The result proved to the author that the irritability gradually falls and becomes zero at 34° — the very point at which the reflexes, under similar conditions, also disappear. No preliminary phase of increased activity is mentioned ; nor is it stated whether or not the air was saturated with water. As a check upon this experiment, more evidence was sought in this way : a brainless frog was hung up in a glass tube, which covered only the upper part of the trunk and left the pelvis and legs not covered in any way. Including the tube just mentioned and connected tightly with it was a larger glass tube of the same form. Thus a hollow jacket was formed around the frog and yet not touching him, and through this jacket could be passed water of different temperatures. It turned out that rapid heating produced at first a rise of excitability (measured by Turck's method) which speedily passed over into a fall even to zero ; while gradual heating pro- duced a steady fall, with no previous phase of heightened excita- bility.

(d) The efferent nerve. This was investigated with the results already reached by numerous observers. Like the afferent nerve it preserves its irritability at a temperature above that at which the reflexes fade away.

(e) The connected muscles. These were investigated with the well-known result. The author found, however, that in dry air

394 W. T. SEDGWICK.

a muscle did not pass into rigor before 45°-50° had been reached ; whilst in moist air it perished at 33°-35°. Its irritability in a moist room quickly increases from 20°-30° and then gradually decreases to 34°.

Archangelsky's conclusion is easily foreseen. The loss of reflex excitability under heating is due, according to him, to a weak- ening of the spinal cord alone.

Like Heinzmann, Fratscherf* working in 1875 in the Jena laboratory under Preyer, does not at the outset undertake to contribute to the discussion of the present problem. Heinz- mann having reached the extremely interesting results described above, it was an important question to ask if acids and alkalies might also be so stealthily administered to a part of a living animal (either brainless or normal) as to cause destruction of tis- sue without having ever produced movement. This question Fratscher took up under the direction of Preyer, and he had already succeeded, as he believed, in demonstrating the truth of the hypothesis, when, by Dr. Foster's paper, his attention was called to the explanation of the effects of thermal stimuli gradu- ally applied, and to the need for a repetition of Heinzmann 's work. This he undertook, and he reiterates all of Heinzmann's results, contradicting some of Foster's statements in a way which will shortly be described. He finds that heat stimuli, as well as acid and alkali stimuli, if only applied slowly enough, may be concentrated so far as to produce tissue-death without giving even a solitary movement.

Rosenthal™ in a brief summary of his " Studies on .Reflexes," published in 1875, states as one result of his work, that cooling depresses reflex-excitability. This result, it will be observed, is practically opposed to the conclusions of Tarchanow, Foster, etc.

In the same year, Freusberg 14 makes use of the experiment of Tarchanow 7 quoted above, and verifies it. He endeavors to explain it upon his theory of " latent stimulation," and, what is of great interest, shows that not only will ice-packing enormously raise the reflex-excitability, but that packing in hot sand will do the same thing, (cf. Archangelsky. 11 )

He distinctly affirms that an explanation is not to be sought for in a general reduction of body temperature, " for this, on the contrary, effects a general inactivity of the organism ; and

TEMPERATURE AND REFLEX ACTIONS. 395

besides, the phenomenon is so quickly produced by the ice-pack- ing that it cannot be ascribed to that cause. "

Freusburg was at once attacked by Tarchanow, 15 M who refused to accept his explanation of the increased excitability seen in a frog packed in ice. Tarchanow states that he prefers an explan- ation offered (he omits to say where) M already some years ago," exsanguinated frog does not show the same phenomenon which he observed in 1871. From this observation he concludes that the blood is an essential element in the experiment, and seeks to account for the facts by supposing that the heightened excitabil- ity is due to an excess of oxygen, the result of cessation of rapid oxidations, or by considering a deficiency of CO* as the active cause, etc., etc.
 * 1) nd states, as showing the falsity of Freusberg's theory, that an

Freusberg 11 returns the attack by showing defects in Tarcha- now's method and obscurity in his results. He seems to me to have decidedly the best side of the question.

The second part of Wundtfs 18 Untersuchungen appeared in 1876, and contains one section devoted to the influence of tem- perature and the time of year upon the reflex-excitability of the frog. He has worked, however, only upon the effects of lower- ing, and not upon the effects of raising the temperature. By em- ploying methods similar to those of Tarchanow 7 and Freusberg 14 (mentioned above) he has substantiated and somewhat extended their results. By ice-packing of the trunk he obtains, like them, an increased reflex-excitability, which, however, passes over speedily into gradual depression, and finally into a condition of complete inactivity under stimulation.

His explanation of the phenomenon is somewhat unlike Freusberg's, which apparently he had not seen, and cannot be given in full at this point. He considers it, however, as due partly to heightened activity of the motor nerves and partly to central nervous changes. He further points out a singular effect of cold upon the spasms caused by strychnia. He affirms that, as is well known, a small dose will produce violent spasms at the ordinary temperature, while he adds that even large doses produce no effect upon a frog in the cold. It is interesting to compare these results with those of Kunde 3 given above.

396 W. T. SEDGWICK.

In closing, Wundt suggests that his experiments seem to offer a sufficient explanation of the various changes which frogs undergo in respect to their reflex-excitability during the various seasons.

The latest contribution to this subject, so far as I know, is embodied in a suggestion offered by Langendorff}* This writer found that stimuli appear normally to travel along the optic nerve, and to inhibit reflex actions to some extent, perhaps by exciting the so-called " inhibitory centres " of Sets- chenow. He recalls an observation of Fubini, that after blinding the reflex-excitability of a frog is increased, sees in it a confirmation of his own idea, and adds that he is inclined to believe the rise of irritability after ice-packing, observed by Tarchanow 7 and Freusberg, 14 to be due to an anaesthesia of the skin, which, if I understand him, no longer sending in exciting stimuli to the inhibitory centres, allows them to relapse into quiet, and thus brings about heightened excitability.

The writer of the present paper was led to take up this sub- ject by a perusal of Dr. Foster's article referred to above, and more especially by certain evidence and conclusions recorded by Dr. Foster which seemed to be scarcely harmonious with well established physiological laws. The results of his investigations (which have now extended over a considerable period) have jus- tified him, he believes, in making still further studies. The pres- ent communication will be devoted chiefly to a review of certain parts of Dr. Foster's paper, and to the description of 6ome new observations bearing upon the problems at stake.

II. The Experiment of Goltz.

As has been stated above, it was pointed out long ago by Goltz that the brainless frog, if allowed to rest in water the temperature of which is gradually raised, behaves wholly unlike the normal frog under the same circumstances. The normal frog leaps away, or, if confined, becomes violent in his attempts to escape as soon as the temperature of the water reaches 30° or thereabouts, while in the same vessel the brainless frog sits motionless until death supervenes.

TEMPERATURE AND REFLEX ACTIONS. 397

This observation was repeated and verified by Dr. Foster, 10 who saw, however, in the behavior of the brainless frog a new problem which had not been touched by Goltz. Goltz's experi- ment no doubt demonstrates as clearly as he meant to have it, a difference between the normal and the brainless frog ; bnt, as Dr. Foster observes, it presents a new difficulty, viz., " why the brain- less frog is not excited to reflex action by the stimulus of the hot water ? "

It might have been expected that a frog in full possession of his faculties would be more acute than a brainless frog in per- ceiving a temperature which was gradually rising to a painful pitch, and more prompt and skilful in his endeavors to escape than his neighbor destitute of a brain and scarcely recovered from a recent profound operation ; but it would not have been predicted that a decapitated frog, whose reflex functions are well known to be keenly alive and even more delicately adjusted and more easily aroused than those of the normal frog, would sit unmoved in the presence of abundant stimuli until it perished from excessive heat.

It is a surprising fact that although provided with a delicate reflex apparatus, ordinarily responding to small heat stimuli quite as well as to acids or mechanical injury, the brainless frog remains perfectly calm in the presence of multitudes of power- ful stimuli which are attacking large areas of his sensitive skin, and makes not a single reflex movement worthy the name. Still more astonishing is it when we learn that during this period of calm, very complex and orderly reflex movements can be evoked by a gentle touch or a drop of dilute acid, proving that the reflex apparatus is not paralyzed, but, for some reason, though wide awake to other and apparently feebler calls, is deaf to thoso of the heat stimuli.

This problem which Dr. Foster has pointed out he has also endeavored to solve. He has extended and modified Goltz's experiment, using for the purpose brainless frogs suspended by the jaw, and immersing the hinder parts to various depths in water whose temperature could be gradually raised. In this way various definite areas of the body-surface could be exposed to the action of gradually-heated water, and his results are described by him as follows :

398 W. T. SEDGWICK.

" Observation 1. If a frog, from which the brain has been removed, be suspended by the jaw, with the legs hanging freely down and the toes dipping into a vessel of water, on gradually heating the water the toes are withdrawn by reflex action as soon as the temperature of the water reaches a little over 30°. The result does not essentially depend on the rapidity of the rise. However slowly the water be heated, the feet are always withdrawn at a temperature of 35° or earlier. Rapid heating may possibly lower the degree at which the feet are withdrawn ; but to this I have not paid particular attention. "Whether heated slowly or rapidly, the feet are withdrawn at about 35° C. or at a lower temperature.

Observation 2. If the whole body, thuB suspended, be similarly im- mersed and heated, no movements (or only the very slightest spasms of the muscles of the legs) take place ; and on still further raising the temperature, the body becomes rigid (rigor cahris).

Observation 3. If both legs be immersed up to the anus and simi- larly treated, they also become rigid without movement either of ihe legs or of any part of the body, gave only a few spasms.

Observation 4. If one leg only be immersed and similarly treated, it also becomes rigid without movements, or with only slight move- ments.

Observation 5. If both legs (or one leg) be immersed up to the knee, they are sometimes withdrawn, but sometimes no movements take place, and the portion immersed becomes rigid. The results in this case are not so constant as when either more or less of the body is immersed.

Observation 6. If the feet only are immersed, they are invariably withdrawn at 35° or under.

Observation 7. If a frog be suspended over a vessel divided by a partition, with water at unequal levels on the two sides, so that one leg is wholly immersed and the foot only of the other leg, and the vessel be surrounded with water the temperature of which is gradu- ally raised, neither the leg nor the foot will be withdrawn, if care be taken that the water on both sides of the partition be equally and uniformly raised in temperature. If, in this last observation, the water on both sides be reduced to the same level, both feet are with- drawn. This result shows that warm air and vapor have not the same effect as warm water, and that the absence of movements is not due to the unavoidable contact of the thighs of the animal with the top of the partition giving some support to the legs, and .thus diminishing the tendency to the withdrawal of the feet."

TEMPERATURE AND REFLEX ACTIONS. 399

It is not difficult to repeat these experiments and to arrive at about the same results. It iB, indeed, my own experience that if no special attention be paid to the rate of heating, and that if it be not too rapid, one will obtain results agreeing essentially with Dr. Foster's. If, for example, a brainless frog be immersed as above described in water at 20 p or 18° C, and the temperature be raised to 40° (by a lamp below the vessel) in ten, fifteen or twenty minutes, events will juetify the above statements.

If, however j a powerful burner be used and the water be heated in muck less time than ten minutes, not even the frog immersed to his fore limbs will remain quiet, but, like the frog with only his feet immersed, will exhibit violent movements. It is easy to prove, and is practically admitted by all observers, that under heat- ing which is at all entitled to be called " gradual," the immersion of an actively reflex frog suspended as described above and im- mersed to the fore limbs or to the anus, will bring about such a state of things that the animal will pass into heat rigor without making a single movement of consequence.

A year before Foster's work was published, Heimmann* had found that by gradual heating of an entire frog, or even of only one hind leg, the temperature of the animal or of the part might get to be so high as to produce rigor and yet without the least disturbance of its general repose. He, however, puts special stress upon the effects of very gradual heating, and makes the important discovery that even a normal frog may be made to perish in the same way without a struggle, provided only that the increase of heat be gradual enough. This statement in- volves a direct contradiction of the statements of Goltz, 6 Tarcha- now 7 and Foster, 10 who have all agreed that under gradual heat- ing the normal frog becomes violent in his attempts to escape. The contradiction is only partial, however, for any one in half an hour can prove to his satisfaction that the three observers are correct ; while FraUcher u has fully justified Heinzmann. The truth appears to be that if the heating be sufficiently grad- ual, no reflex movements will be produced even in the normal frog ; if it be more rapid, yet take place at such a rate as to be fairly called " gradual," it will not secure the repose of the normal frog under any circumstances, though it will do so for the reflex frog if only enough of his skin be immersed, while

400 W. T. SEDGWICK.

it will fail if only a small portion be dipped ; again if the temperature rises so rapidly as scarcely to be called "grad- ual " iD its upward progress, not even the reflex frog will remain quiet, though wholly immersed, but, like the normal frog, will exhibit violent movements.

Heinzmann did not experiment with immersion of the feet only, so that an interesting question was left after the paper of Dr. Foster appeared, as to whether or not Heinzmann would have succeeded in keeping the frog quiet by his extremely gradual heating had he immersed only so small a portion of the animal as the feet. This question has been answered in the affir- mative by FratscherJ* who found that he could warm even the normal frog to the point of rigor by immersing merely the feet. My own work points in the same direction ; and we may take it as settled that Foster was mistaken when he came to the conclu- sions laid down in Obs. 1. I believe that I can explain, how- ever, the result which Dr. Foster obtained. In my own case, at least, I found that it was due to reflex movements, caused by dry- ing. When the feet only are immersed a very large part of the body is exposed to the dry air of the room, and the naturally moist skin of the frog dries, producing reflex movements. In a moist chamber it is not very difficult to raise the temperature of the water in which the feet are dipping, higher than 35° without causing movement.

It is plain from what has been said that the smaller the por- tion of the animal immersed the more difficult it is to heat with- out producing movements, and the more gradual must be the rise of temperature. Moreover, since, as the part immersed gets smaller, the surface exposed to outside stimuli gets larger ; while, at the same time, the heating must be more gradual (thus pro- longing the period of exposure) and the tendency to movements gets greater, the slight stimulation due to drying, and perhaps to the coincident cooling of the not immersed parts, becomes an important factor in the experiment ; a factor which is less im- portant and can be neglected when much of the body is immersed, but which may lead to error when the feet only are dipped. At least one safe conclusion maybe drawn at this point. It is plain that if Goltz had slightly varied the conditions of his experiment; if his brainless frog had not been in contact with

TEMPERA TURE AND REFLEX A CTIONS. 401

the heated water by a tolerably large surface, he would have failed to demonstrate by this experiment that difference between the normal and the headless frog for which he was seeking.

"We have next to consider why it is that the reflex (and the normal) frog, in fall possession of healthy end-organs to detect and sensory nerves to transmit painful impressions, may never- theless exhibit total indifference to temperatures which are gradually raised so high as to kill the tissues immersed. Differ- ent explanations have been offered by Goltz, 6 Heinzmann 8 and Foster 10 respectively, and that of Goltz may be conveniently referred to first. I have not seen his original communication upon the subject, but if one may judge from the context in the description of the experiment given in 1869, it appears that Goltz 6 considers the lack of movement to be due to lack of " per- ception." He regards the failure to move under abundant stimuli as showing this lack of perception, not wanting in the normal frog, which therefore displays movements. If this be the theory of Goltz to account for the quiet of the reflex frog it is plainly defective, since the reflex functions of the brainless frog surpass in delicacy those of the normal one.

The theory of Heinzmann, 8 who approached the subject from an entirely different standpoint and while endeavoring to solve a different problem, may conveniently be deferred until the theory of Foster, 10 who was, I believe, the first to raise the point at issue and who has given the subject its most exhaustive treatment, shall have been reviewed.

After describing the results of his investigation in the passage quoted above, Dr. Foster writes as follows (p. 46):

" The above observations show that when the toes (alone immersed in water) begin to be affected by the high temperature, say 30° C, the stimulus of the hot water causes a reflex action which results in the withdrawal of the foot. When the whole leg or body is immersed, the same stimulus is still at work, but no reflex action occurs. What is the reason that reflex action is absent ?

The following explanation is, perhaps, the first to offer itself. The warmth applied to the leg diminishes the irritability of the nerves or of the muscles, or of both ; and thus the impulses generated by the warm water in the sensory terminations of the nerves of the foot are not carried up to the cord, owing to the diminished irritability of the

402 W. T. SED0WI0K.

sciatic trunk, or, being so carried, the reflex process taking place in the cord cannot manifest itself on account of the diminished irrita- bility of the muscles or motor nerves.

But this v REFLEX ACTIONS. 409

2. Kunde, Dr. F. 18G0. Der Einfluss der Warme und Electricitat auf das Riickenmark. Virchow's Archiv, 18, 357.

3. Cayrade, Jules. 1864. Recherches critiques et expirimentales eur les mou Yemen ts reflexes. Thtse pour le doctorat en m^decine, Paris, 1864.

4. Weir- Mitchell, S. Jan., 1867. On retrogressive motions in birds produced by the application of cold to the cervical spine, with remarks on the use of that agent as an aid in physiological investiga- tion. Amer. Journal of the Medical Sciences, No. 105, p. 102.

5. Richardson, B. W. May, 1867. On the influence of extreme cold on nervous functions, etc. Medical Times and Gazette, 1867, p. 489.

6. Goltz, F. 1869. Beitr'age zur Lehre von den Functionen der Nervencentren des Frosches. Berlin, 1869, p. 127, etc.

7. Tarchanow, J. 1871. Ueber die Wirkung der Erwlirtnung resp. Erkiiltung auf die sensiblen Nerven, das Hirn und Ruckenmark des Frosches. Bulletin de Tacademie imp£r. des sciences de St. Peters- burg. Tome XVI (1871), p. 226.

8. Heinzmann, A. 1872. Ueber die Wirkung sehr allmiiliger Mn- derungen thermischer Reize auf die Empfindungsnerven. Archiv fur die gesammte Physiologie, Bd. VI (1872), p. 222.

9. Tarchanow, J. 1872. Zur Physiologie der thermischen Reflexe. Original paper in the Russian. Abstract in Hofman & Schwalbe's Jahresbericht, Bd. I (1872), S. 520.

10. Foster, Dr. M. 1873. On the effects of a gradual rise of tem- perature on reflex actions in the frog. Journal of Anat. and Physi- ology, viii, 45 ; also, Studies from Physiological Laboratory, Univ. Cambridge, 1873, p. 36.

11. Archangelsky, P. 1872. Ueber den Einfluss der Warme auf das Nerven- und Blutgefuss-System des Frosches. Original paper in the Russian. Abstract in Hofman & Schwalbe's Jahresbericht, Bd. II (1873), S. 555-559.

12. Fratscher, C. 1875. Ueber continuirliche und langsame Ner- venreizung. Jenaische Zeitschrift, N. F. II (1875), S. 130.

13. Rosenthal, J. 1875. Studien uber Reflexe. Monatsberichte der Berliner Akad., 1875, S. 419.

14. Freusberg, A. 1875. Ueber die Erregung und Hemmung der Th'atigkeit der nervosen Central organe. Pfliiger's Archiv, Bd. X (1875), S. 181.

15. Tarchanow, J. 1875. Augmentation des actes rt flexes sous rinflu- ence du froid. Gazette m£d. de Paris, 1875, p. 287.

410 W. T. SEDGWICK.

16. Tarckanow, J. 1875, De l'influence de l'augmentation de Poxy- gene ou de l'acide carbonique dans le sang sur lee actes reflexes de la grenouille. Gazette m£u\ de Paris, 1875, p. 426.

17. Freutberg, A. 1876. Kalte als Keflexreiz. Archiv fiir exper. Path, nnd Pharm. Bd. VI, S. 49.

.18. Wundt, Wilhelnu 1876. Untersuchungen aur Mechanik der JServem und Nervencentren. Zweite Abtheilung, S. 59. Stuttgart, 18.76.

19. Zangetulorff, 0. 1877. Die Beziehungen des Sehorganes zu den reflexhemmenden Mechanismen des Froschgehims. Archiv fiir (Anat. und) Physiologie, 1877, S. 435.

20. Cyon, E. Ueber den Einfluss der Temperaturveriinderungen auf die centralen Enden der Herznerven. Pfluger's Archiv. Bd. VIII, S. 340.

Hall and Motora (1887)
Hall, G.S., and Y. Motora (1887), “Dermal Sensitiveness to Gradual Pressure Changes”,

American Journal of Psychology, 1, 72-98.

http://www.archive.org/details/americanjournalo01austuoft

Heinzman 1 undertook a more serious experimental solution of the question whether a thermal stimulus could increase so gradu- ally as to be unobserved by the sensory nerves so that death would finally supervene without any movement of either resistance or escape on the part of the animal. Frogs were heated (a) locally with a leg in water gradually warmed, and (b) totally by sitting on a cork floating in a cylinder of water, though it was much harder to boil intact and normal than brained or reflex frogs without sensation enough to cause motion. Their sensory seemed to conform to motor nerves in this respect. Fratscher 1 repeated these experiments, heating very gradually, by means of a lamp applied to the small bulbous end of a tube communicating with the large vase of water in which the animals were exposed, and found he could even induce rigor mortis in normal frogs by immersing only a small portion of the body in the fluid. Acid and alkali stimuli he found might also be applied so gradually as to kill the tissues without stimulating movement. The researches of W. T. Sedgwick, 2 to whose discussion of the topic the reader is referred, seem to show conclusively that in the case of heat this cannot be due to a diminished irritability of the spinal cord by reason of the heat carried into it by the blood, and that organs with a basis of protoplasm cannot so far reverse its laws as to completely lose functional power with no pre- liminary phase of increased activity.

Scripture (1897)
Scripture, E. (1897), The New Psychology.

http://www.archive.org/details/newpsychologyscr00scririch

How great the just perceptible change can be made to become by making the rate of change extremely slow is a matter that still remains for investigation. It is worthy of note that it has been found possible in 5 1/4 hours to actually crush a frog's foot, without a sign that the pressure was felt, by screwing down a button at the rate of 0.03 mm. per minute. A similar experiment showed that a live frog can actually be boiled without a movement if the water is heated slowly enough ; in one experiment the temperature was raised at the rate of 0.002 C. per second, and the frog was found dead at the end of 2½ hours without having moved. 1 If a frog can be crushed or boiled without any evidence that he has noticed it, it is at least an interesting question of what can be accomplished in this direction with human beings.

1 The literature on these experiments with frogs includes Heinzmann, Ueber die Wirkung sehr alluutliger Aendenuigen thermischer Reize aitf die Empfinduugsnerveu, " Archiv f. d. ges. Physiol." (Pfluger), 1872, vi. 222. Fratscher, Ueber conti nuirUche und langsame Nervenreizung, " Jenaische Zeitschrift," 1875, N. F. ii. 130. Sedgwick, On the Variation of Reflex Excitability in the Frog induced by changes of Temperature, " Stud. Biol. Lab., John Hopkins Univ.," 1882, 385.

Morgan (1904)
The Journal of experimental zoology (1904)

ANN HAVEN MORGAN - TEMPERATURE SENSES IN FROG's SKIN

pp85-86

http://www.archive.org/details/journalofexperim35harr

Frogs respond to variations in temperature by visible motor reac- tions. This was established experimentally by Kunde ('60), Cayrade ('64), Goltz ('69), Tarchanow (71, '72), Archangelsky ('73), Rosenthal ('75), Freusberg (75), and Wundt ('76). The means of stimulation were partial or complete immersion in warm or cold water, dipping in warm or cool dilute acid, and ice packs and hot sand baths. From treatment of these kinds one group of workers (Kunde, '60; Richardson, '67; Weir-Mitchell, '67;

Rosenthal, '75) maintained that cold caused a depression in reflex excitability, except in the case of ice packs, which in- creased it (Richardson, '67; Weir-Mitchell, '67; Wundt, '67), and another group were of the opinion that heat properly ap- pUed also caused excess excitability (Cayrade, '64; Goltz, '69; Tarchanow, '71, '72; Freusberg, '75).

When cold or heat are applied very gradually to a frog the reactions decrease in extent and vigor. There has been a good deal of dis- agreement in the literature, regarding reactions to gradually applied stimuli. The question was opened by Goltz ('69), who immersed normal and reflex frogs in water of gradually increasing temperatures. When slowly stimulated up to 30°C., the normal frog became violent, but the reflex frog remained inert. Goltz's main purpose had been to show the difference between the two conditions in the animal, and he immediately declared the lassi- tude of the reflex frog due to its brainless state. By the same method, Tarchanow ('71, '72) secured similar results on normal frogs. The next year Heinzmann ('72) continued similar ex- periments from the point of view that the sensory nerves might be affected by a stimulus increasing in intensity so slowly that destruction of the nerve would result before a reaction could occur. Normal and reflex frogs were heated with the expected results to both of them, and these were explained as due to the very gradual succession of the stimuli. In 1875 Fratscher re- peated these expermients with identical results. The quiet normal frogs of Heinzmann and Fratscher were thus pitted against the violent normal frogs of Goltz and Tarchanow, but the main conclusion seems to have been that no reaction would result if stunulation were applied with sufficient gradualness.

Foster ('73) had previously questioned Goltz'^ -^^atement that brainless frogs would give no reaction to stimuli to which normal frogs reacted so vigorousl}^ He immersed reflex frogs 'locally and totally' and obtained xevy difl'erent results in the two cases. When large areas of the body were immersed there was no re- sponse, but when only the toes were dipped, no matter how gradually the heat was increased, they were alwaj^s withdrawn at about 35°C. This peculiar result was explained by Foster

on the ground that immersion of the larger areas heated the blood, which in turn warmed the spinal cord and reduced its irritabihty. With the stimulation of the small area no such general warming could take place, and hence the normal irritability of the cord was retained and the vigorous response followed.

Certain puzzhng phases immediately presented themselves, and Sedgwick ('82) repeated the experiments upon which this explanation was based. He suspended the reflex frogs in the manner described by Foster and at once discovered that in this upright position the heart was practically empty and could not possibly circulate the blood as stated by Foster.

From this tangle of statements the best e\ddence seems to show that the reflex frog will respond to heat at certain degrees, no matter how gradually it is appKed, but that the extent and vigor of these responses may be reduced by the graded application of the stimulus