[cameron-brownlee] temperature AND THE FROG 69 



Summarizing, more particularly for mammals, Pembrey concludes: 

 ^"The limit of high temperatures appears to be fixed by the point 

 at which the proteids of the body begin to coagulate." The experi- 

 ments of Maurel and Lagriffe indicate that 39° to 40° is the maximum 

 temperature which can be survived by the frog, and that temperature 

 can only be survived for short periods.^ 



Some of the experiments of Babâk and Amerling^ on R. fusca 

 and R. esculenta have a bearing on the present enquiry. Thus: 



A specimen of R. fiisca became motionless and ceased to react 

 after immersion in water in a thermostat at 40-5° C. for one hour, 

 and after a further 15 minutes at 42° was in complete heat rigor and 

 dead. A specimen of R. esculenta, treated in the same way, while 

 motionless and no longer reacting to stimuli after one hour at 40-5°, 

 showed no trace of muscle rigor and began to breathe half a minute 

 after removal from the water. After a further 30 minutes at 42°, 

 on removal this frog w'as motionless, did not react, but was not in 

 heat rigor. After ten minutes reflex movements and breathing 

 appeared, and after twenty minutes, locomotion. 



Another specimen of R. esculenta was kept continuously in a ther- 

 mostat for 3 hours at 40°, one hour at 41°, one hour at 42°, and almost 

 half an hour at 43°. The slight pressure caused in removing it from 

 the thermostat produced a marked outbreak of stormy reflex move- 

 ments after which it very rapidly recovered. 



R. fusca ceased to react after two and one-half hours in a ther- 

 mostat at 39°, and only recovered very slowly. 



Babâk and Amerling found also that this effect is not due to 

 want of oxygen as claimed by Winterstein,^ since the power of resis- 

 tance is inverted in the two species in oxygen-free atmospheres. 

 The time of year at which their experiments were carried out is not 

 stated. 



Becht^ has shown that the "heat paralysis" induced in nervous 

 tissue when the frog attains a temperature about 34°, is not due 



^ Pembrey , loc. cit. p. 824. 



^ Maurel and Lagriffe, Compt. rend. soc. biol., 1900, vol. ccxvii, p. 432; quoted 

 by Tigerstedt in Winterstein's "Vergleichende Physiologie," vol. Ill, 2nd half, 

 p. 90, 1914. 



^ Babâk arid Amerling, "Untersuchungen iiber die Wârmelàhmung und die 

 Wirkung des Sauerstoffmangels bei Rana fusca und Rana esculenta," Zentralbl. f. 

 Physiol., 1907, vol. xxi, p. 6. 



^ Winterstein, "Ueber die Wirkung der VVarme auf die Biotonus der Nerven- 

 zentren," Zeitschr. f. allg. Physiol., Bd. I, 1902; quoted by Babâk and Amerling, 

 loc. cil. 



* Becht, "Some observations on the nature of heat paralysis in nervous tissue," 

 Amer. J. Physiol., 1908, vol. xxii, p. 456. 



