CYTOLOGICAL CHANGES IN KGGS OF RAT. 325 



ly degenerate. They might be expected to enter the uterus, if at 

 all, as mere shells and scattered cytoplasm. The zona is either 

 broken or absent at this stage. 



CON< i.i -ION. 



I "Howing ovulation most of tin- changes undergone by tulul 

 rat eggs are distinctly abnormal. The central position of the 

 spindle, the occurrence of three uni-. and one binncleate cell, the 

 coar-enin- .f cytopla-mic r-truct tire, the < >1 MT\ ati< >n that division 

 is more or le regular acn.rdiiu '" the number of " nuclei" which 

 are pre-ent, and tin- discovery i-j" a fe\v two. three and four cell 

 Stages may be thought t<> indicate -me tendency towards normal 

 de\elopniein in certain of the nnt'eriili/ed eggs. < >n the con- 

 trar\ , the t.n I that the central -pindle i- ran- and always degener- 

 ate, that only three uninucleate cell- were found, the i:reat pre- 

 ponderain e of multiniH leate cell>. and the fact that only very 

 enerate fragment- are found near the uu-rii-. make it neces- 

 Bary to < onclnde that although certain auto-re^ulati\ e processes 

 may OCCtir in a few ova, a <letmiti- t\pe of degeneration is the 



rule. 



lUMI.I. x.KAI'UV. 

 Athias, M. 



'09 I-i-- |.lii'ii'iiin-ii ' .;aaf en \ 



il';itii--i-- i \\>-f. ! I .34: 1-23. 



Barfurth, D. 



'96 \ViNtnh iiln-r ilif I : .1. i. Entwickl.. 



Bonnet, R. 



'99 l.i'.t Ct bel \\ :: 'Ilirrrll I' : ' it. U. Entwickl.. 



9: .v 

 Bischoii, T. L. 



*44 Sur la m.itur.itinu <-t la > lain- jx-rt.li<, . noinme et des mam- 



iniirn'-i iniIi-|M-ii(aiiii-i!.' Ann. Sci. Natur.. 3: 



p. ; i .'. > : U 

 Charleton. H. H. 



'17 i-.it'- : the Unfertili* M BIOL. BULL.. 33: 



-338. 

 Flemming, W. 



'85 i"l>iT<li- Bililunn \iin Ri. hti. - rn t..-im I'tuergang 



Gra.iti- II-T Fullik<-l. Ar.h i. An.it. u. I-.'iitwicklutu-^ . I 1885. 



221-244. 

 Hartmann, C. G. 



'16 Development of the Opossum. Jnurn. Morph.. 27: 1-83. 

 Heape, W. 



'05 Ovuluti'in ami Degeneration of the Ova in tiie Rabbit. Proc. Roy. Soc. 

 LonMun, ~(> b. 



