CELL SIZE AND MI-TABOLIC ACTIVITY IX AMPHIBIA. 35! 



Standard solutions were made by preparing a stock solution of 

 X 10 oxalic acid by weight, X '10 barium hydroxide standardized 

 against this, and X 10 hydrochloric acid standardized against the 

 barium hydroxide. Phenolphthalein was used as an indicator in 

 preparing the standards and in the actual determinations. A 

 preliminary aeration was run with the animal in the respiration 

 jar, but without the collecting bottles, for one hour. The col- 

 lecting bottle- wen- then placed in the series, and aeration carried 

 on for a measured length of time, 8-24 hours. At the end of thi> 

 aeration the collecting jars were removed and the excess of 

 hydroxide titrated immediately by means of N 10 hydrochloric 

 acid. The amount of hydroxide used by the carbon dioxide was 

 thus obtained by difference, and the amount of carbon dioxide 

 collected computed as C() per gram body weight per hour. 

 All determinations were made on starving animals and at room 

 temperature, \\hii h varied between 20 and 23 (\ 



Triio-^ iji5) describes a method of determining carbon dioxide 

 by passing air through a tower containing barium hydroxide and 

 jja>> beads. This method would be more accurate than the 

 one iiM-d here, but the method was unknown to the writer at the 

 tune when the experiments described in this paper were under- 

 taken. 1 1 i> fell that the method used here yields results of com- 

 parative value, which i> all that is needed. Truog shows that 

 the barium carbonate present with the hydroxide does not hinder 

 accurate titration, and that the barium hydroxide method of 

 determining carbon dioxide is very accurate. 



Red blood corpuscles were used for measuring cell size. Most 

 of the animaU u>ed were those on which carbon dioxide deter- 

 mination:- hail already been made. The animal was killed either 

 by pithing or \\ith chloroform, and blood taken either from tin- 

 heart by mean- of a syringe or from the tail vein. Thin MIKMI- 

 \\ere made on slides, dried in the air and stained \\ith Wright's 

 Main. In main ca>es blood counts on both red and white 

 corpu>clc> were made, and tissues fixed in Bouin'-< fluid for section 

 later in order that other cells might be measured. The blood 

 count > and tissue cell measurements are not included in the 

 present paper. The latter agree reasonably well with the re-ult- 

 gixen for red blood cells, while blood counts are found to \ary 

 widely with the physiological condition of the animal. ( M course 

 in general animals with larger cells have smaller number-. 



