NUCLEAR SIZE OF NERVE CELLS 13 
types of cells in each stage, the number of cells measured and 
the range of variation for each. The results are shown graphi- 
cally in the curves which follow the table. 
A study of these results together with the plotted curves in- 
dicates a number of fundamental conditions. In all of the 
stages in each of the three groups of cells measured, there is a 
wide range of variation in the size of the nucleus. This cannot 
be charged to the normal swelling of the nucleus just before 
mitosis, for the same variation is present in the cells of the bee 
that had lived through the winter and in the queens studied. 
That variation is an ever-present condition in all living things 
is a truism, but when we attempt to indicate which organ or 
tissue 1s responsible for the variation most of the observations 
have been simply a record of the organic fact of variation. This 
study claims that the cells and their parts such as the nuclei 
are the variable factors that are responsible for the variation in 
the tissue or organ. Any explanation of the cause of such vari- 
ations has to recognize the part played by cells. It seems to the 
writers that this natural’‘and normal variation plays an important 
part in explaining such conclusions as Crile comes to in regard 
to the effects of shock. Before we can accept his conclusions, 
we must determine what is the normal range of variation for the 
group of. cells that he studied. It would have been a relatively 
easy problem to indicate a definite tendency beginning with young 
adults and passing to the winter bee by simply taking some of 
the large cells in the young adult with nuclear diameter of 12 
micra and comparing them with those that measure 7.9 micra. 
This would give a definite shrinkage with age; but when the 
average of some forty cells is taken, the total is 9.26 micra for 
the young adult, and 9.45 for the winter bee. We interpret the 
difference to be due to the normal variation present in these 
cells and do not regard the larger average for the winter bee in 
nerve cells of type I as a measure of the extent of change that 
as come with fatigue or age. 
The second inference to be drawn from these measurements 
is the independent sequence of growth changes in these three 
types of nerve cells. There is a more or less rhythmic variation 
