144 JOSEPH HALL BODINE 
those for Melanoplus differentialis) are based upon individuals 
taken during the entire summer and hence represent values for 
both young and old animals and can be considered as fair averages 
for the species. That such an average must be based upon the 
water contents of both young and old individuals is quite evident, 
since the preceding section shows that the percentage of water 
of an animal decreases with increasing age. It is of some interest 
to mention here that in another species of grasshopper, Chorto- 
phaga viridifasciata, the percentage of water during the winter 
months drops to a minimum of 65 per cent, while in the same 
animal when growing the water content is raised to 75 per cent. 
Since the percentage of water of an animal is thus dependent 
upon and so easily modified by external factors, such as tempera- 
ture, moisture, etc., it is difficult to get data to show that definite 
species differences in water content exist. The present results 
for ^Melanoplus f. rubrum and Dichromorpha viridis, where the 
animals were under the same conditions, seem to show, however, 
that such a condition might occur. Babcock {9), in discussing 
'metabolic water,' concludes that the water content of insects 
depends largely upon the nature of the food eaten, but does not 
show that those living upon the same foods may have different 
percentages of water. 
c. Changes during the riormal life-cycle. Some changes in the 
percentage of water during the life-cycle of grasshoppers have 
been shown in a preceding section. Chortophaga viridifasciata, 
however, because of its peculiar habit of living as a nymph during 
the winter and 'hibernating,' affords opportunity for further 
studying the various changes in water content which normally 
occur during such a period. 
Table 2 gives results obtained for 565 specimens and shows 
that during this period the percentage of water falls from 72 
per cent to 65 per cent. This minimum of 65 per cent is perhaps 
as far as desiccation can be carried without injurious results, and 
is a factor of some importance in the economy of the organism. 
Somewhat similar rhythmic variations in the water content of 
animals are shown for the frog by Donaldson (10), and for the 
potato-beetle by Breitenbecher (8) . These 'hibernating' animals 
