PARTHENOGENETIC CLEAVAGE OF THE ARMADILLO OVUM. 55 



ovocytes of the same generation in that they can never go through 

 the process of ovulation and therefore cannot develop normally. 

 A very small percentage of these ovocytes continue the matura- 

 tion process to the extent of completing the first maturation 

 division; a still smaller proportion (only three out of hundreds 

 of cases examined) complete the second maturation; while the 

 remainder, over 90 per cent., are struck by the processes of 

 follicular atresia and either go into early cytolysis or enter upon 

 a period of parthenogenesis. It is with the latter contingency 

 that the present paper deals. 



ABSTRICTION OF THE DEUTOPLASMIC .MATERIAL AND ITS 



SUBSEQUENT FATE. 



The condition of equilibrium, just described and illustrated 

 in text-figure 2, is normally disturbed only by ovulation, but, 

 in the case of ovocytes whose normal history has been cut short 

 by the fertilization of an ovum and the formation of a corpus 

 luteum, the equilibrium may also be upset by the marked changes 

 in the chemical environment incident to follicular atresia. The 

 follicle in which atresia has set in rapidly decreases in size through 

 the loss of follicular fluid, but, even before the amount of fluid 

 has materially diminished, its chemical composition is clearly 

 altered, for it no longer stains deeply with the ordinary cytological 

 stains but remains pale gray under hsematoxylin treatment. Just 

 what the nature of the change is I am unable to determine, but 

 there can be no question as to its radical character. As atresia 

 continues, the lumen of the follicle gradually disappears, partly 

 through the loss of fluid and partly through the ingress of cells 

 from the disintegrating granulosa layer of the follicle. With 

 this radical alteration of chemical environment the ovocytes 

 show marked changes, whose significance it is our problem to 

 determine. 



The first act of the ovocyte entering upon parthenogenetic 

 development is the abstriction of the deutoplasmic mass from 

 the formative protoplasm. That this is a practically universal 

 phenomenon can scarcely be doubted for there are in the present 

 material literally hundreds of instances of it, and one can with 

 confidence look for some stage of the process in every follicle 



