WATER CONTENT AND RATE OF METABOLISM 163 
Starvation results in marked and rapid losses in body weight, 
water, and solids, but the greatest and quickest loss seems to be 
of water. Closely correlated with these losses is a decrease in 
the rate of COo output. Various species of animals seem to have 
different rates of respiratory exchange, but all show a higher 
rate for the younger individuals. Increased temperatures cause 
increased rates of CO2 output, while lower temperatures seem 
to have the reverse effect. Ingestion of food by starved animals 
greatly increases the rate of CO2 production. By a comparison 
of these data with those found for mammals, striking similarities 
are found to exist, and these would seem to indicate that the 
problem of insect physiology, although at first seemingly unre- 
lated to that of mammals, has, in fact, many points in common 
with it. 
SUMMARY 
1. The percentage of water an animal (grasshopper) contains 
decreases with age and increasing body weight, up to a minimum 
for the species. 
2. Different speckles of the same general group, living upon 
similar foods, may have different percentages of water. 
3. During the active life-cycle of Chortophaga viridifasciata, 
the water content falls to a minimum during 'hibernation,' 
rises again to a maximum when 'hibernation' is broken up, and 
then again falls to a minimum as the animal grows old. These 
changes seem to be due to the effects of temperature and advanc- 
ing age. 
4. Water and temperature are the controlling factors in 
Chortophaga's emergence from 'hibernation.' 
5. Different species of grasshoppers studied, under similar 
conditions, survive starvation for different periods of time, e.g., 
Melanoplus differentialis, 172 hours; Melanoplus f. rubrum, 144 
hours, and Chortophaga viridifasciata, 170 hours. 
6. Starvation results in losses of body weight, water, and 
solids, the greatest relative loss being of water. With water 
alone, losses are lower than with nothing. 
7. Larger individuals tend to lose relatively greater amounts 
during starvation. 
