DESICCATION AM) CARBON DIOXIDE PRODUCTION'. 26l 



critical comparisons of the known and unknown indicator 

 solutions. 



Wherever the respiration time of animals appears in this 

 paper, it is to be taken as the time in seconds required by the 

 animal, or animals, to excrete sufficient carbon dioxide to change 

 4 cc. of standard indicator solution from pH 7.8 to pH 7.2. No 

 attempt was made to determine the actual quantities of carbon 

 dioxide produced by the animals, since all comparisons were made 

 on the basis of time required for the excretion of snlticient carbon 

 dioxide to produce this standard chani^' in j>ll value. 



The roinrol of the movements of the various animals in the 

 lirator) hamber was on the basis of tropi-tic responses to 

 livJii or contact. In no instance \\ essation of activity 

 lined thioirJi mechanical means, and no experiments have 

 i re. oided in this paper where the animal \\a> mo\in- when 

 the carbon dioxide determinations \\en- made. Movements 

 eoiiM e.:-ily be dete. ted through marked in. tie- in re-pi- 



rat ion time. 



run on all experiments. The control animals 



\\eie kepi under the same conditions as the experimental animals 



pi ihe\ \\eie noi desiccated and exchishe of one control in the 



experiments on / >, neither controls nor experimental 



animal- v I during the experiment. 



The anim ils were weighed in previously adju-ied \\ei;.Jiing 

 boi tie- immediaieh after the carbon dioxide determinations were 

 made. This pr,.\ -d preferable to werj^m- before the detenni- 



Iiatioils \\eie made -hue it reduced till- stimulating ellect of 



handling and con-c. |iicnlly the animals came to n-st in the 

 respiratory appaiatu- more quickly. The animals undoubtedly 

 lost \\ei^ht in the animal chamber of the respiratory apparatus in 

 some instances and gained weight in Other instances, depending 

 upon the staieof de-iccatic>n, but the gain or loss in the respiratory 

 chamber \\a- so slight compared with the loss in the desiccator 

 that it \\as disregarded. All weights are given in milligrams as a 

 matter of COI1\ enielice. 



The general |>ro> cdure was the same for all of the experiments 

 conducted. The normal respiration time of the experimental 

 animal \\ as determined ; three consecutive readings were averaged 

 for each determination. The-e readings varied somewhat 



