494 



MINNA E. JEWELL 



For the next experiment a new method of calculating the areas 

 was devised. The average of the length, width, and depth of the 

 body was found, and with this as the diameter the area of the 

 body was calculated as a sphere. The area of the tail was com- 

 puted by regarding it as a rectangle from the base to the level 

 at which it begins to taper rapidly to a point, and as a triangle 

 from this level to the tip. These areas were doubled to give the 

 two sides of the tail, and added to the area of the body, already 

 found, to give the total area of the tadpole which is expressed in 

 square millimeters. The area computed by this method is prob- 

 ably considerably less than the actual area of the tadpole, but 

 it was hoped that by selecting animals similar in shape, the ratios 

 of computed area to actual area would be about the same. 



Three sets of three tadpoles each were measured, weighed, and 

 the CO2 production in distilled water determined for six successive 

 days with the following results : 



The CO2 per day per gram of tadpole, 4.56 cc. for the larger 

 ■size, 4.66 cc. for the second size, and 5 cc. for the smaller size, 

 shows a slight increase in CO2 production per unit of weight with 

 a decrease in size. In order to compare the relative area, weight, 

 and CO2 production of the three tadpoles, all were expressed in 

 terms of per cent of the larger size, taken as 100 per cent (last 

 three columns). The weight and CO2 production vary by differ- 

 ences of +1.3 per cent and +2.83 per cent in the second and 

 third sizes, respectively, while the area and CO2 production vary 

 by differences of —8.8 per cent and —12.5 per cent, suggesting 

 that the normal CO2 production of tadpoles in distilled water 

 is much more nearly correlated with body weight than with area, 

 as is the case for warm-blooded vertebrates. 



