348 Annals Entomological Society of America _[Vol. VII, 
life, possibly as the direct result of a mere aggregation of matter— 
such a histolysis as above described, would reabsorb and re- 
distribute this extra matter in such a way as to clear the cells of 
all inactive substances. During hibernation in the frog (Mor- 
gulis quotes Leonard) a similar process of histolysis and shifting 
of the nucleocytoplasmic relation in favor of the nucleus takes 
place. Without doubt, the cells are rejuvenated in the frog 
during hibernation—the case of Synascidians has already been 
stated. Lillie has found that fresh water Planarians if ex- 
posed to starvation, ultimately return to an embryonic form. 
These experiments have been confirmed by Schultz (50). 
Childs found in his experiments on Planaria that starvation 
and regeneration both lead to rejuvenation—starvation differs 
from hibernation in that the life processes go on at a high rate 
in the former while they are sunk almost to zero in the latter. 
Starvation does not lead to the lowering of the water content 
as hibernation does, except in the nervous system. ‘The con- 
ditions of the cells in the hibernating or in the starving 
insect are quite different. In the hibernating animal, the 
condition is one of overfeeding and probably of old age— 
that is, the accumulation of inactive substances in the cell 
is very great. - In the starving animal on the other hand, 
the conditions are morphologically extremely young and 
physiologically old (underfed). | Child compares cells in the 
overloaded condition to an ovum and the starved young 
cell to a spermatozoan. Loeb (32) has found that fertiliza- 
tion increases the permeability of membranes. The action of 
fertilization is the same as rejuvenation. A similar rejuvena- 
tion may take place by change in feeding as Calkins (8) has 
found to be true in his experiments with Paramoecium—where 
no conjugation took place if a change in feeding were made at 
the proper time. This agrees with Child’s theory that rejuven- 
ation can be brought about by a change in the chemical process 
of metabolism. 
One characteristic of overfed Planarians according to Child 
is the physiological isolation of parts due to the overloaded 
condition of the cells with inactive bars to metabolism in the 
cytoplasm. This isolation leads to fission or to a senescence, 
i. e., a lowering of the rate of the metabolic processes. In 
Codling moth larve that are about to hibernate, I have found - 
very similar conditions to exist—first, the vital processes are 
