1903.] in the Nerves of Warm-blooded Animals. 275 



Series III. 



Pigeon. Experiments B n and B T Sciatic, all the rest Median. 



Experi- 



Hours 



Temp, 

 of nerve 

 cham- 

 ber. 



Temp. 



Neg. var. 

 initial 

 = a. 

 -00 1 v. 



Neg. var. 

 final 



= b. 



Irrita- 

 bility 





ment 

 No. 



post- 

 mortem. 



of hot 

 bath. 



quotient 

 _ b 



a 



Notes. 





h. m. 















C fb 



3 15 



28 



53°6 



0-30 











Cold bath accidentally omit- 

 ted. The nerve was much 

 contracted longitudinally 

 after heating. 



C fc 



4 



30 



53-0 



0-75 











Nerve contracted. No "ne- 

 gative variation " after 

 heating, but large posi- 

 tive current escape ob- 

 served, not abolished by 

 crushing. 



B" 



4 15 



38 



52 -5 



0-25 



0-12 



0-481 



Neg. var. rapidly diminish- 



B k 



4 30 



38 



52 -0 



0-56 



0-17 



0-30 J 



ing. 



BJ" 



3 



37 



50-0 



0-61 



0-18 



0*30 





B« 



2 



30 



45 -3 



0-30 



1-05 



3'5 





The experiments can be summarised thus : — 





Normal temp, 

 of animal. 



Temp, of incr. 

 neg. var. 



Temp of dim. 

 neg. var. 



Temp, of abol- 

 ished neg. var. 



1 



! Frog 





39—40° C. 



39-41° 



40—42° 



: Rabbit 



37—41°* 



42 -3° 



44 -3—47 '7° 



48—49° 





40—42 -5t 



45 -3° 



50° 52—53° 



It is seen that the effect of heat occurs in three stages. In the first, 

 at a temperature of 1 — 2° above that of the animal, the negative 

 variation is increased. In the second there is diminution, recovered 

 from at the lower temperatures (4° over normal) if the nerve is cooled 

 longer than the standard time, not recovered from at the higher (6 — 7° 

 over normal), and finally the negative variation is permanently 

 abolished, 8° over normal in the rabbit, 10° in the pigeon. 



While the mammalian and avian nerves show quite small individual 



* Pembrey (Schafer's ' Text-book,' vol. 1, p. 790). The higher limit for the 

 rabbit is from unpublished observations of Dr. Pembrey, which he has very kindly 

 furnished me for this paper. 



t Corin and Yan Beneden, 'Arch, de Biol.,' Gand., 1887, vol. 7, p. 265. 



x 2 



