n8 Shiro Tashiro 



were left in Ringer's solution, and then the rate of the gas production 

 is determined with the different nerves removed at successive inter- 

 vals of time from the Ringer's solution for twenty-five hours. The 

 interesting results given in Table IV not only show that CO 2 from the 

 fresh nerve is not due to bacterial decomposition, but it also indicates 

 that when such abnormal decomposition sets in, the output of gas 

 takes a sudden jump. This Table further shows that the vital process 

 by which CC>2 is produced gradually slows up as the tissue approaches 

 death, indicating that the decrease of CO 2 production is parallel to 

 the decrease of irritability of the nerve. 



Increase of CO 2 on Stimulation. The most convincing evi- 

 dence of all that CC>2 is formed by a vital process is the fact that 

 a stimulated nerve gives off more CO 2 (Part II) indicating the 

 presence of normal metabolism in the living nerve which is accelerated 

 when the nerve is stimulated. Thus we may safely conclude here 

 that like any other tissue or organs, the nerve, too, respires whether 

 it has a nucleus or not, and that the rate of C0 2 production is pro- 

 portionate to its weight, other things being equal. 



CO2 PRODUCTION FROM STIMULATED NERVE 



We have now come to our main inquiry, namely, is there any 

 chemical basis for irritability? Just what relation exists between 

 nervous activity and chemical changes is the question that a biologist 

 should consider before he attempts to build any conception of the 

 real dynamics of living matter. For it is the phenomena of excita- 

 bility in the nerve fibre that has stood so long in the path of under- 

 standing protoplasmic irritability in general. As for the brain, it is 

 now established that certain chemical changes are involved during 

 stimulation and that definite chemical changes are associated with 

 pathological cases either in its chemical composition 23 or in the for- 

 mation of abnormal metabolites. 24 Aside from the confused facts 

 concerning histological changes in the ganglion cells of fatigued ani- 

 mals, Hill has observed, using Ehrlich's method of methylene blue 



23 KOCH and MANN: Archiv of neurology and psychiatry, 1909, iv, p. 44. 



24 DIXSON: Journal of physiology, 1899-1900, xxv, p. 63; CROFTAN: American 

 journal of the medical sciences, 1902, p. 150. 



