136 Shiro Tashiro 



fatigue easily. These considerations suggest very strongly that the 

 absence of fatigability in the nerve as measured by the ordinary 

 methods, is not a question of absence of metabolism, but merely the 

 speed by which these two processes come to an equilibrium. 



Although we have an infinite number of facts still unexplainable, 

 by our present knowledge of nerve physiology, we have established a 

 few new facts around which we may build up some idea concerning 

 this most essential phenomena of living matter, i.e., irritability. 

 As to the true nature of the nerve impulse, I can only confess my 

 ignorance. 



SUMMARY 



1. All nerve fibres give off CO 2 . The resting, isolated nerve of 

 the spider crab produces 6.7 X icr 7 gram per 10 milligrams per ten 

 minutes. The frog's sciatic 5.5 X io~ 7 grams. 



2. When nerves are stimulated they give off more CO 2 . .The 

 nerve of the spider crab claw produces 16. X io~ 7 gram when stimu- 

 lated, the frog nerve 14.2 X icr 7 grams. The rate of increase of 

 C0 2 by stimulation amounts to about 2.5 times. 



3. The CO 2 output of resting nerve is due to a vital active process. 



4. Anaesthetics greatly reduce the carbon dioxide output of nerves 

 and dry seeds. 



5. Mechanical, thermal and chemical stimulation also increases 

 the carbon dioxide output of nerves. 



6. Single dry living seeds (oat, wheat, etc.) react in most par- 

 ticulars similar to nerves as regards their irritability, relation to 

 anaesthetics, mechanical stimulation and carbon dioxide outputs. 



7. The general conclusion is drawn that irritability is directly 

 dependent upon and connected with tissue respiration and is primarily 

 a chemical process. These results strongly support the conception 

 that conduction is of the nature of a propagated chemical change. 



To Prof. A. P. Ma thews, under whose direction I have carried on 

 these experiments, I express my appreciation and gratitude. For 

 many suggestions, I am under obligation to Dr. F. C. Koch. 



