NUMBER OF OVA: ALBINO RAT 431 
DISCUSSION 
The various topics will be discussed in the order in which the 
data have just been presented. 
1. Comparison of the weights of the ovaries and the number of ova 
on the right and left sides 
The data in table 1 show that the right ovary has, as a rule, 
only nine-tenths the weight of the left, but nevertheless contains 
the same (or a slightly greater) number of ova. 
TABLE 11 
The weights of both ovaries with ages 
THE AGE CORRESPONDING TO THE AGE CORRESPONDING TO 
THE WEIGHT OF BOTH THESE AVERAGE THESE AVERAGE 
OVARIES OVARY WEIGHTS IN DAYS OVARY WEIGHTS IN DAYS 
(MY OBSERVATION) (DONALDsON, 715) 
mgm 
6.5 25 26 
10.0 59 55 
Wiles) 57 57 
PAL 92 67 
It is interesting to note further that, so far as my observations 
go, the corpora lutea appear simultaneously in both ovaries when 
these reach the weight of more than 10 mgm. (for one ovary). 
They are not present earlier (table 1), and in no case do they 
appear on one side only. Sobotta (10) found that, as a rule, in 
albino rats the mature ova are discharged at the same time from 
both ovaries. 
We might expect this relation in other mammals which nor- 
mally produce two or more young at a birth, but we have not 
found any observations on this point. 
It is usually stated that in man only one ripe ovum at a time 
is discharged from either of the ovaries, and therefore in man the 
corpus luteum should appear on one side only. Whether the 
left or right human ovary supplies most of the ova or whether 
both ovaries give off the same number is not known. One strik- 
ing relation worth emphasizing here is that variations in the 
