366 



II \KYKY M. SMITH. 



there are either two maxima or a sustained maximum. This 

 results from the fact that the maximum for different individuals 

 of the same species varies. It is just this variation between 

 individuals which complicates comparative results on cell size, 

 especially between closely related species. It is not associated 

 with the metabolic activity of the animal, sex, or any other factor 

 which can at present be indicated. Reference to Chart i will aid 

 in understanding the variations here discussed. 



32 



ZO 



16 



ll 



f, 



72. 



CHART ib. \'ariation in red blood cell size for Xe<.ti<rus (solid line) and Rana 

 pipiexs (broken line). Explanation as for Chart la. 



B. Carbon Dioxide Production. 



i. The weight of the animal is the primary factor which com- 

 plicates the results on carbon dioxide production. The general 

 fact is that the carbon dioxide output as measured by unit 

 weight increases as the weight decreases. Reference to the 

 results for Necturus will emphasize this fact. For convenience 

 these are listed in Table Y., the individuals being taken in order 

 of their weight. 



