434 HAYATO ARAI 
We have seen that in general the weight of ovaries in which the 
corpora lutea are not present increases with the growth of the 
rat, either in body weight or body length. With the appear- 
ance of the corpora lutea the weight of the ovaries becomes 
more fluctuating, owing perhaps to individual variations in the 
addition of the corpora lutea. 
Thus these fluctuations just noted may have no meaning ex- 
cept as showing a greater variation in the growth rate of the ovary 
at this period. Even when the weights of the ovaries found by 
myself and those given by Donaldson are arranged according to 
the increasing body length, the results show a high degree of sim- 
ilarity to those which were arranged according to increasing 
body weight (table 11). My observations show that with the 
appearance of corpora lutea there is a sudden increase in the 
weight of the ovaries, and we may infer, therefore, that the in- 
crease in the weight of ovaries with increasing body weight, as 
noted in ‘The Rat,’ chart 21, is also due to the same cause. 
In woman the ovaries are said to atrophy after the meno- 
pause, so the weight of ovaries might show a decrease after this 
event. Such weight alterations, as well as the period at which 
the maximum weight is attained, are not recorded in the litera- 
ture. It would therefore be of interest to extend these observa- 
tions to human ovaries. 
We may now summarize the various factors which are respon- 
sible for the increase in the weight of the ovaries. In addition to 
the formation and enlargement of the individual ova, these are 
the growth of interstitial tissue, the number of the mature fol- 
licles; of degenerated follicles, small or large; of corpora lutea, 
fresh or old, as well as the content of blood. The exact amount : 
of blood, however, has not been determined, yet it is worth while 
to note here that either a hyperaemic or anaemic state is recog- 
nizable according to the different physiological states of the 
ovary in relation to heat. 
