CRITICISMS AND CONCLUSIONS. 5 1 



from the ovarian capsule or oviduct; but, unfortunately, he does not 

 give the dimensions, and his figures are too diagrammatic to serve as a 

 means of determining size. Kirkham has apparently overlooked the 

 above statement, for he says that Tafani makes no mention of the method 

 used to obtain living eggs. Kirkham (19076, p. 70) procures them by 

 killing a female soon after ovulation is supposed to have occurred, re- 

 moving the ovaries and Fallopian tubes to a slide, and gently teasing 

 them with fine needles until the eggs are seen to drop out ; he then trans- 

 fers them to the stage of the microscope for study. Kirkham does not 

 state in what fluid he studied the eggs. The medium, however, is impor- 

 tant, since it might, if not like the natural fluid in osmotic action, either 

 swell or shrink the egg. We have already shown that a prolonged stay 

 of eggs in the oviduct in the several cases results in an increase in their 

 size, the eggs used for comparison being also subjected to precisely the 

 same treatment as those from the oviduct. Since Kirkham's determina- 

 tion of the time of ovulation is in error by 10 hours or more, it is a little 

 doubtful whether all his eggs were in a normal condition. 



F. MATURATION PROCESSES, 

 l. Germinative Vesicle. 

 It is agreed by all investigators that the germinative vesicle is at 

 first very near the center of the egg, and that it becomes more eccentric 

 as the time of its transformation into the first spindle approaches. 

 Tafani and Gerlach both state that its membrane becomes irregular 

 and disappears soon after the chromosomes have begun to form. 



2. First Spindle. 



Chromatin. 

 Tafani (1889, P- 2I ) believed that by the rupture of the germina- 

 tive. vesicle the nucleolus escaped as an angular chromatophilous mass 

 and moved toward the surface of the egg, where it gave rise to the chro- 

 mosomes, while the remnants of the vesicle degenerated in the cyto- 

 plasm. We have observed that the cluster of chromosome fundaments 

 sometimes has the appearance of such an angular mass, and it is possible 

 that Tafani mistook this for the nucleolus. He figures it as in the act 

 of slipping out of the germinative vesicle. In Sobotta's opinion (1895, 

 p. 44) the chromosomes in eggs which produce but one polar cell are 

 formed from the chromatin of the whole nucleus, not merely from that 

 of the nucleolus as was claimed by Holl (1893), whose conclusions are, 

 in Sobotta's opinion, unreliable because of the poor preservation of his 

 material. Sobotta's statement (1895, p. 44) that the chromosomes are 

 very irregular in form before they become arranged in the equator of 

 the spindle and his illustration of the condition (Taf. 4, fig. 9, 9a) must 

 really relate to the second spindle, for they are both based on eggs from 

 either the periovarial chamber or the beginning of the oviduct ; but such 

 eggs must have already passed beyond the stage of the first spindle, as 



