A, E.. MOORE . 617 



last two used as the true value, figures being given to the nearest 

 5 seconds. When the time extended over 5 minutes it was possible 

 to make only one or two readings, the time being given to the nearest 

 half minute. 



The first point to be settled is: Does a nerve trunk give off carbon 

 dioxide at a rate equal to that shown by muscle and by central 

 nervous system tissue? For the purpose of answering this, equal 

 weights of sciatic nerve, sartorius muscle, and brain were taken from 

 the same frog. Measurements of the rate of acid production were 

 made as soon as the tissues were removed from the body and at in- 

 tervals of an hour subsequently. It was found that if the tissues 

 were kept in a small quantity of Ringer's solution during the time 

 intervening between the measurements the acid production increased 

 again after 2 hours, coincident with the rigor and opacity of the 

 muscle. If, however, the pieces of tissue were kept in a large quantity 

 of neutral Ringer's solution during the time interval, there' was a 

 falling off in the rate each hour for about 4 hours. Table II and the 

 corresponding graphs (Figs. 1 and 2) show the relative respiratory rates 

 of the three types of tissue and the decrease in rate with time. A large 

 number of experiments of this character were made, and in all cases it 

 was found that central nervous system tissue and muscle showed a high 

 rate, while sciatic nerves always gave a rate of much lower order; 

 viz., 10 to 30 per cent of that of the other tissues. Just what part 

 of this carbon dioxide is due to the metaboHsm of the axis cylinder 

 and what to the connective tissue cells of the nerve trunk remains 

 to be determined. 



The question of greatest interest in connection with the metaboUsm 

 of nervous tissue is: Does the functional activity of the nerve cause 

 an increase in the production of carbon dioxide? Tashiro has an- 

 swered this in the afiirmative, and states that stimulation of a nerve 

 more than doubles the rate of carbon dioxide production. With a 

 view to getting additional evidence on this point, I stimulated 

 sciatic nerves with induction shocks while the acid measurements 

 were being made.^^ For this purpose fine copper wires were led 

 into the tube beside the cork. The ends of the wires were bent 



^1 Moore, A. R., Pfoc. Soc. Exp. Biol, and Mei., 1918-19, xvi, 66.1 



