NUCLEAR SIZE OF NERVE CELLS 75 
in nuclear size in old adults is due to fatigue or old age or both, 
how are we to explain the larval and pupal change? The larvae 
of the bee are inactive so that they are more like the pupa than 
is usual in insects. Metabolism is very active during the larval 
period but this can hardly result in fatigue to nuclei in the brain. 
One would expect that the changes that take place during the 
metamorphosis in the pupa would drain heavily on the energy 
of the insect, and yet the same rhythmic nuclear changes in size 
continue through this period. So far as activity is concerned 
these stages give us the two extremes, the larvae and pupae 
at rest, the adults of summer extremely busy and the win- 
ter workers relatively inactive. If there is a definite nuclear 
change with work, the stages selected should give us some in- 
dication of it. In place of definite nuclear change with age, we 
find a constant variation which tends to be rhythmic. 
CONCLUSIONS 
1. In the honey bee worker there is a definite variation in the 
nuclear size of the nerve cells studied. 
2. Changes in nuclear size dependent on the life cycle are un- 
like in cells of different type. 
3. The changes in nuclear size can not be explained as due to 
the effect of old age or fatigue. 
