142 Shiro Tashiro 



hydroxide solution is introduced through V to d and f, where drops 

 are formed as before. 



As stated above, this apparatus can be used for the combined 

 purposes of qualitative detection, quantitative estimation, and com- 

 parative determination of the output of C0 2 from the various biolog- 

 ical specimens. It has a decided advantage over the other in the 

 fact that we have a control drop, side by side, under exactly the same 

 conditions, and that the comparative estimation of C0 2 produced by 

 different specimens can be made very easily and accurately. The de- 

 tailed method of procedure is described under three different headings : 



(a) For the Qualitative Detection of Carbon Dioxide. After 

 the apparatus is cleaned and dried, 11 a weighed tissue is placed on the 

 glass plate and hung on n and m of the chamber A, and no tissue in 

 the other chamber. After both chambers are closed with the stop- 

 pers S and R and sealed with mercury, they are so filled with mercury 

 that the remaining volumes in both chambers are now exactly the 

 same. The chambers are now evacuated and washed with pure air. 

 When evacuation and washing with pure air is complete, the pressure 

 is made atmospheric, by adjusting with the nitrometer the connec- 

 tion between A and B is then closed with stopcock L. If any CC>2 

 is given off by the tissue, the desposit of carbonate will soon appear 

 on d, while in the control chamber the drop on f remains perfectly 

 clear. In order to avoid any possible error of a technical nature this 

 experiment is repeated by exchanging the chambers, now using 

 chamber B for the respiratory chamber and the other A as a 

 control. 



(b) For Comparative Estimation of CO 2 from Two Different 

 Samples. By repeated quantitative experiments, it was found 

 that the speed with which the first precipitate appears and the sizes 

 of the deposits on the drops at d and f represent corresponding quanti- 

 ties of carbon dioxide. Thus with remarkably simple means, we can 

 determine simultaneously the comparative outputs of the gas from two 

 different tissues or from the same tissues under different conditions. 

 The method of procedure is best illustrated by the following example. 

 Two pieces of the sciatic nerve are isolated from the same frog and 

 exactly weighed. One piece is laid on one glass plate, and the other 



11 This, too, can be cleaned and dried without being taken apart. See foot- 

 note on p. 138. 



