WATER CONTENT AND RATE OF METABOLISM 
157 
concludes that no reason exists for assuming a surface relation 
to hold. 
As already pointed out for the grasshopper, smaller indiA^duals 
have per unit of weight a greater COo output than larger ones. 
And since the area of the surface of an animal is usually estimated 
from the body weight by means of the formula of Aleeh {22), 
based on the law that surfaces of similar solids are proportional 
to the two-thirds power of volume, it is of some interest to see 
in how far the rate of CO2 output of the grasshopper can be 
thus expressed. In the following table are given a few examples 
of the ratio of CO2 output to body weight and to the two-thirds 
power of the weight, respectively. 
CO2 ACCORDING TO THE 
WEIGHT OF ANIMAL 
CO2 ACCORDING TO BODY WEIGHT 
TWO-THIRDS POWER OF THE 
BODY WEIGHT 
grams 
2.16 
0.001000 
0.001290 
1.35 
0.001037 
0.001204 
1.11 
0.001174 
0.001224 
1.08 
0.001186 
0.001226 
1.05 
0.001215 
0.001236 
1.01 
0.001219 
0.001232 
1.01 
0.001263 
0.001276 
0.94 
0.001310 
0.001282 
It is evident that the more constant values are obtained by 
using the two- thirds power of the weight, and so far as the 
results here reported are concerned, the conclusion might reason- 
ably be drawn, that the surface law holds for grasshoppers as 
well as for mammals. But in view of the complex nature of the 
problem, more extensive data will be necessary before this 
relation can be considered as definitely established. 
c. Effects of temperature. The influence of temperature on the 
respiratory exchange is a somewhat disputed question because 
comparatively few observations are made under standard con- 
ditions. Krogh {21), however, in summarizing the work of 
various investigators, points out that different animals respond 
in different ways, but in general, with cold-blooded forms, in- 
creased temperatures cause increased respiratory rates, while 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 32, NO. 1 
