1914] Longevity of Insects 345 
minimum size. It is possible that by diminishing the volumne 
it increases its absorbing capacity. Hibernation is also unlike 
starvation in its characteristic quiescence, for animals when 
starved are very active. In hibernation also,there is no regen- 
eration of tissues while in starvation this often occurs. 
Hibernation seems to have a close connection with the 
maturation of the reproductive organs. Tower has found that 
those potato beetles that have gained sexual maturity, do not 
succeed in passing through the hibernating period successfully. 
Sexual maturity is seldom gained before hibernation in the 
second brood of this insect. This activity is greatest imme- 
diately following hibernation. He finds that the germ cells 
remain in the female as oocytes during hibernation and develop 
rapidly after hibernation. There. are two generations in all 
climates—it would be supposed, Tower says that at high 
temperatures, breeding would go on continually but every 
alternating brood has a rest period before breeding goes on— 
this rest period is estivation or hibernation depending on cli- 
mate. All grape leafhoppers that have reached sexual maturity 
are unable to pass through the period of hibernation success- 
fully—only the very immature males and females live through 
the winter to produce the next brood (according to Johnson 
27). 
Morgulis quotes the case of the Rhein salmon which makes 
a sojourn of from six to nine and a half months in the Rhein, 
remaining without food, developing in the meanwhile, its sexual 
elements at the expense of fat and proteids accumulated before 
hand. Holmes states that the period of great feeding preceding 
hibernation supplies food for that period and for the develop- 
ment of the reproductive organs which are to come into full 
activity immediately after hibernation. Hibernating insects 
seldom arrive at sexual maturity before this period is over. 
Newell found that the female cotton boll weevils which have 
hibernated continue to deposit eggs for a much longer time than 
the others. Morgulis claims that insufficient feeding effects 
the ovaries the most; since these organs seem to often develop 
during hibernation, it is very improbable that inanition takes 
place during this period. Loeb quotes Giard and Caullery as 
having found that a regressive metamorphosis occurs in Synas- 
cidians and that the animals hibernate in this. condition. The 
muscles of the gills of these animals are decomposed in their 
