294 JOHN C. DONALDSON 
for the males and females have been plotted separately. It 
will be seen that the curves for the two sexes are essentially 
parallel, but that the one for the females, marked by crosses, 
indicates a smaller relative value for the medulla, and at the end 
of the female curve the relative volume becomes stationary. 
Both curves show a rapid decrease in the relative volume of the 
medulla until about the age of puberty, then in the males an in- 
50 100 150 260 250 300 
Chart 1 The change in volume of the medulla expressed as a percentage of 
the whole adrenal gland. Dots, e, males, individual values. Crosses, +, females 
individual values. 
crease and in the females no further loss. Dr. Jackson, in some 
recently completed work (Jackson, ’18), has found essentially 
the same relative decrease in the chromaffin tissue in the rat. In 
his rats, however, he did not find any differences between the 
sexes. His results, as he has kindly told me, were not arranged. 
to bring out any such differences which might exist. 
The recent work of Elliot and Armour (11), and Lewis and 
Pappenheimer (716) shows that in the human adrenal just after 
birth there is a rapid degeneration and absorption of the inner 
