282 H. M. KINGERY 



of ova has not been settled one way or the other for two reasons : — 

 no one has taken the time and pains to examine a complete 

 ('liickenlose') series of ovaries, and second, there have not been 

 any definite characteristics by which a young egg-cell might be 

 recognized. Concerning this second point these authors state 

 further : 



Xiin ist es von eineni von uns (v. Winiwarter, '00) nachgewiesen 

 worden, dass das Ei der Saugetiere im Laufe der Wachstumsperiode 

 eine Reihe von Kernveranderungen durchmacht, welche so characteris- 

 tisch sind, dass sie mit Sicherheit erlauben, einen jungen Oocyten von 

 alien iibrigen epithelialen Zellen des Ovariums zu unterscheiden. Von 

 diesem Prinzip ausgehend, hat sich schon damals einer von uns (v. 

 Winiwarter) dahin ausgesprochen, dass eine Neubildung von Eiern 

 nur dann als bewiesen gelten konne, wenn die als neugebildete Eier 

 angesehenen Element e die characteristischen Kernmetamorphosen 

 der ersten Entwickkmgsstadien des Ovariums erkennen lassen ("que 

 les pretendus ovules de nouvelle formation montreraient les meta- 

 morphoses nucleaires caracteristiques des premiers stades de developpe- 

 ment de I'ovaire"). ('08 a, p. 613-614.) 



It seems to me that this is rather an unwarranted assumption, 

 made by von Winiwarter himself in 190D and repeated by von 

 Winiwarter and Sainmont in 1908. The account given by these 

 authors of the development of these egg-ceUs, is very carefully 

 worked out. The egg-cells, in their development, pass through 

 certain stages which have been very carefully characterized, 

 and then every one undergoes degeneration. It is not quite 

 clear just what justification there is for the dictum that any 

 cells of new formation, in order to be considered egg-cells, must 

 pass through the same stages in their development as the earher 

 formed cells which degenerate and disappear. It would seem 

 that the ultimate fate of any cells of new formation should have 

 some bearing on the question of whether they are to be considered 

 definitive egg-cells. If these cells, formed after birtb, can be 

 shown to develop into the definitive ova, if they can be traced 

 through all the stages up to eggs in mature Graafian follicles, it 

 would seem that the question of whether or not their earlier 

 development was like that of the cells formed in the embryo, 

 was a matter of slight importance. 



