372 B. F. KINGSBURY 



(fig. 14). The Graafian follicles that develop during the period 

 of sexual maturity are almost always uni-ovular in the cat, are 

 more regular and uniform in shape and the ova are characterized 

 by a markedly different structural appearance as compared with 

 the ova of the pre-sexual Graafian follicles as noted by von Wini- 

 warter and Sainmont. 



A very frequent accompaniment of the degeneration of the 

 Graafian follicles of the pre-sexual period in kittens approaching 

 sexual maturity, may be incidentally mentioned, namely, the 

 occurrence of polar spindles, polar body formation and a form of 

 degeneration of the ovum by fragmentation, simulating a par- 

 thenogenetic cleavage. It is unnecessary to consider here the 

 question of their parthenogenetic nature. Similar conditions have 

 been described in several forms. Bonnet has considered and 

 rej ected their parthenogenetic character. In the ' ' Hertwig Hand- 

 buch, " Waldeyer has discussed them and pronounced against 

 their parthenogenetic significance, while Hertwig regards them 

 as essentially a beginning parthenogenesis. In the cat they 

 occur most abundantly in old kittens (ca. four months) in the 

 large Graafian follicles that have begun degeneration as atresia 

 folliculi. While no particular search for them has been made, 

 four polar spindles and several fragmenting ova (fig. 28) were 

 encountered in a single ovary and were found to occur in four 

 ovaries of this period. In illustration of the typical and 'normal' 

 appearance, figures 26 and 27 are submitted, showing a first 

 polar body and second polar spindle (?) in the same ovum. That 

 there is not a factor peculiar to the period of adolescence which 

 determines the introduction of maturation, is evinced by the oc- 

 currence of the polar spindle formation in a degenerating folli- 

 cle of an adult ovary. That the phenomenon is not simply an 

 indication that the growth period had been completed and the 

 follicle essentially mature when it enters upon atresia, is also 

 shown by the occurrence of a polar spindle in an obviously young 

 Graafian follicle. In most instances, however, the follicles in 

 which polar spindle formation occurs are of large size. The con- 

 stant correlation is that with degeneration of the follicle. There 

 appears to be, therefore, some factor connected with atresia 



