334 Annals Entomological Society of America [Vol. VII, 
The irregularity of the results given in the next to the last 
column show that there is some other factor involved in the 
determination of the longevity of starving larve at different 
temperatures The most probable factor is the rate of metabolic 
processes for it is the most closely connected with temperature 
and nutrition, of any of the vital processes. Since the rate of 
growth and the rate of metabolism will determine how long the 
insect can live on the reserve material in its body. If the data 
of Table 5 is plotted in a similar manner to the data of Chart I, 
the graph on Chart II is obtained. 
But if it is true that the rate of growth and of Metabolism 
determine the longevity it is necessary to bring another factor 
into consideration before we can explain why a two days treat- 
ment at a low temperature will decrease this rate when the 
insect is placed at a high temperature. 
Growth changes in rate with advance in age but is not the 
process that results in death for while growth is due to the 
establishment of a constant relation between the nucleus and 
the cytoplasm and therefore must finally reach a stage where 
the growth is stopped, senescence always results in a decrease 
in weight which cannot be accounted for by any theories of 
growth according to Robertson (43, 44). Still a fall in the 
rate of metabolism accompanies old age—hence, we must con- 
clude that there is another factor than growth that determines 
this rate of metabolism. It has been determined that the speed 
of the metabolic processes decreases with age—therefore, it 
may be determined by a measure of senescence. The progress 
of senescence has been defined variously by several investi- 
gators. Minot (35) basing his theories on certain truths, 
which others have used in supporting the theory that a nucleus 
can control but a limited mass of protoplasm (Sachs and 
Boveri), has measured the rate of senescence by growth. This 
has been shown to be improbable as before stated by Robert- 
son and by Loeb (30) and Moore (36) who found that the 
temperature co-efficient of growth (2.8) is very different from 
the temperature co-efficient of longevity (1000). 
Minot finds that senescence results from a gradual shifting 
of the ratio between nuclear and cytoplasmic substance (Kern- 
plasma relationship) to the side of the cytoplasm and from the 
differentiation of the cells which accompany this change. This 
