VASCULARITY IN THE NERVOUS SYSTEM 453 



Lucas, then, and probably Adrian, basing their views upon 

 certain characteristics observed in the conduction of the nervous 

 impulse, seem to believe that it is chemical rather than physical 

 in nature. 



Direct evidence for this attitude is found in the work of 

 Tashiro, who supports by strong experimental evidence, seconded 

 by persuasive arguments against objections and contrary views, 

 the thesis that every nervous process is accompanied by a definite 

 change in carbon-dioxide production, indicative of a change in 

 metabolic activity, and hence that such processes are essentially 

 chemical in nature. It may be worth while to quote his con- 

 clusion (Tashiro, '17, p. 107): 



Concerning the nature of the material basis of the nervous impulse 

 we can only say that it appears to involve that part of the chemical 

 transformations in protoplasm which result in the production of carbon 

 dioxide. Farther than this we cannot go at present. But it is certain 

 that it has a chemical basis. Whether it has also a physical basis, 

 such as a change in state of the colloidal substratum of the nerve, or 

 not, we cannot yet say. Who shall write the chemical reaction of the 

 future, embracing not only the energy exchange, but the change in 

 psychism as well? 



(P. 108.) Three kinds of change occur, then, in our brains when 

 the nerve impulses are passing — -an electric change, a chemical change, 

 and a psychical change. Which is the fundamental change? 



A number of objections have been urged against Tashiro's 

 work, which, moreover, seems in some particulars to involve 

 considerable changes in views hitherto held concerning nervous 

 action; and in spite of the strength of his evidence and arguments, 

 the majority of physiologists appear to be disposed to reject it 

 at the present time. It has received, however, rather striking 

 support from the work of Baglioni (loc. cit.), who shows that, 

 despite the earlier evidence to the contrary, there is a definite 

 production of heat in the central nervous system during activity 

 which seems to be parallel with the carbon-dioxide evolution 

 demonstrated by Tashiro in peripheral nerves and ganglia. 

 Moore, however (loc. cit.), has failed to confirm Tashiro's obser- 

 vations and is led to the conclusion that the processes underlying 

 the nervous impulse do not produce carbon dioxide. 



