142 JOSEPH HALL BODINE 
comprising nymphs and adults of Melanoplus f. rubrum and 
adults of Dichromorpha viridis and Melanoplus differentialis. 
It is evident from an examination of this table that considerable 
variation in the body weights for the different species exists. 
These can be explained by a consideration of the differences due 
to species, age, and random variations. It will be noted, for 
instance, that of the species studied, Melanoplus differentialis 
is by far the heaviest, reaching a maximum of 2.9 grams. Range 
in weight for Melanoplus f. rubrum is of interest, since weights 
for both nymphs and adults are given, and these show that as 
the anunals become adults there is a progressive increase in 
body weight up to a maximum for the species. JVIales never 
reach the same maximum weights as females, and this is not due 
primarily to development of masses of eggs by the older females, 
since in nymphs this relation also holds. Consequently any 
comparison between males and females of the same weights will 
not necessarily be between those of the same age. Different 
conditions, such as food supply, development of reproductive 
elements, etc., modify the maximum weights of animals, causing 
some variation among individuals of the same age as shown for 
Melanoplus differentialis, where the animals are of approximately 
the same age and show rather large variations in body weights. 
Closely related to these differences in body weights of the 
animals are the changes occurring in the percentages of water. 
With increasing body weight and age, a progressive diminution 
in the relative water content takes place, as shown especially 
by Melanoplus f. rubrum, where nymphs have an average maxi- 
mum of 77.6 per cent and adults an average minimum of 72 
per cent. That this diminution in water content is related to 
age, and not to body weight, is shown by a comparison of these 
results with those for Melanoplus differentialis, where the ani- 
mals are of the same age, but differ in body weights, and have 
approximately the same percentage of water. A similar result 
has been found by Hatai (4), for the albino rat, in which the 
percentage of water during the life-span decreases from 87.2 
per cent to 65.3 per cent and bears no relation to body weight, 
but depends primarily upon the age of the animal. It will also 
