NUMBER OF OVA: ALBINO RAT 447 
As was shown in table 2, during relatively early stages, for 
instance at twenty days after birth, many follicles containing 
ova from 40 to 60 uw or more in diameter were found, and again 
in the rat at twenty-six days after birth there were found large 
numbers of well-developed follicles, which cannot be differenti- 
ated from mature follicles by mere examination (table 2); yet, de- 
spite the presence of these larger follicles, there is no evidence of 
ovulation in these younger rats. 
Runge (’06) stated that enlarged follicles are by no means un- 
- common in ovaries of young children. In the first year of life 
he found follicles of considerable size, and in the second year 
still larger ones, some having a diameter of 135 yu. In the third 
year degenerate follicles were also found, and he concluded that 
the maturing of the follicles begins early. Loeb (11) also found 
in the guinea-pig, eighteen days old, relatively large follicles in 
the ovaries which were yet small in size. 
Though to my regret I have not studied the relation between 
the stroma and the development of the ovaries, or the internal 
secretion of the ovaries and its relation to their development, yet 
the observations of many investigators, as well as my own, indi- 
cate that the period of puberty is induced principally by the rip- 
~ ening of the ova in the follicles. 
In the absence of coitus it is difficult to detect any special 
stimulus as the cause of the first ovulation or those which follow. 
It naturally suggests itself that influences arising outside of the 
ovaries may determine the rupture of the mature follicles, and 
one turns to the various glands associated with the reproductive 
system as possibly concerned. ‘Thus the hypophysis and supra- 
renal glands in albino rats are larger in the female than in the 
male, the differences in size between the two sexes appearing usu- 
ally somewhat before puberty (Hatai, 713), thus indicating greater 
activity at that time. 
Again, the hypophysis has an intimate relation with the re- 
productive organs. It is also known that the thyroid changes in 
size during menstruation in man, and in the mammary glands, 
according to the recent studies of Myers (16) on the rat, the 
branching of the ducts goes on at an unusually rapid rate about 
