138 , JOSEPH HALL BODINE 
special interest are: changes occurring with age, differences due 
to species and sex, the effects of starvation and hibernation, as 
well as problems dealing with the various phases of metabolism. 
Results of such nature obtained for higher forms have contri- 
buted much toward the advancement of various theories of 
growth, senescence, etc. (Child, 1; ^lathews, 2; Almot, 3), as 
well as to our knowledge of changes in organisms which are 
closely related to age, sex, etc. (Hatai, 4). 
The present investigation deals with such problems as the 
percentage of water during growth, starvation, and 'hibernation' 
in different species of grasshoppers, and also the rate of meta- 
bolism as indicated by determinations of the amounts of carbon 
dioxide given off by the animals. 
MATERIAL AND METHODS 
A. Material 
Grasshoppers were used in all the followmg experiments. 
These animals have been found to be excellent material because 
of the ease with which they can be obtained, kept under usual 
laboratory conditions, and handled in experiments. They are 
sufficiently large to be used individually, and this is of great 
miportance because most of the physiological work heretofore 
done on insects has been concerned with masses rather than with 
individual animals. 
The following species were used: ]Melanoplus femur rubrum, 
Alelanoplus differentialis, Dichromorpha viridis, and Chorto- 
phaga viridifasciata, and they will be discussed in the order 
given. 
]\Ielanoplus femur rubrum DeGeer, the red-legged locust, is 
perhaps the most common grasshopper found throughout the 
entire United States. Its general life-history is practically 
typical ; eggs are laid in the late summer and earlj^ fall and remain 
over winter; nymphs hatch in early summer, and by the last 
of July and early part of August, in the vicinity of Philadelphia, 
adults are found. It occurs in rather large numbers throughout 
the entire summer. The average length of the body of adult 
