122 J. p. HILL. 



To this process of elimination of surplus deutoplasm he 

 applies the name " deutoplasmolyse," and states that " Ce 

 phenomene consiste dans I'apparition de lobules vitellins 

 multiples, en nombre tres variable, t\ la surface du vitellus au 

 niveau du pole vegetatif. Ces bourgeons a pen pres tous de 

 meme grandeur, les uns etaut cependant un pen plus vohimi- 

 neux que les autres, apparaissent dans le voisinage des globules 

 polaires et presentent la structure du deutoplasme. lis sont 

 formes de vacuoles claires, a I'iuterieur desquelles on aper9oit 

 parfois de petits grains vitellins, dont il a ete question plus 

 haut. . . . Ce processus de deutoplasmolyse devient 

 manifeste surtout apres I'expulsion du second globule polaire, 

 pendant la periode de la fecondation. 11 peut etre tres 

 accentue, au stade du premier fuseau de segmentation et au 

 debut de la segmentation de I'oeuf, notamment sur des ovules 

 divises en deux et en quatre (figs. 59, 61, 62, d)." It would 

 therefore appear that, whilst in Dasyurus the surplus deuto- 

 plasm is eliminated always prior to the completion of the 

 first cleavage and in the form of a single relatively large 

 spherical mass, in Vesperugo it is cast oif generally, though 

 not invariably, before cleavage begins, and in the form of a 

 number of small separate lobules. 



List of Refeeences. 



"94. Asslieton, R. — " A Re-investigation into the Early Stages of the 

 Development of the Rabbit,"' ' Quart. Jonrn. Micr. Sci.,' vol. 34. 



'98. " The Development of the Pig during the First Ten Days," 



' Quai"t. Jonm. Micr. Sci.,' vol. 41. 



'98. " The Segmentation of the Oviim of the Sheep, with Obser- 

 vations on the Hypothesis of a Hypoblastic Origin for the 

 Trophoblast," ' Quart. Joum. Micr. Sci.,' vol. 41. 



'08. '* The Blastocyst of Capra, with Some Remarks upon the 



Homologies of the Germinal Layers of Mammals,"' * Guy's 

 Hospital Reports,' vol. Ixii. 



'09. " Professor Hubrecht's Paper on the Early Ontogenetic 



Phenomena in Mammals ; An Appreciation and Criticism," 

 ' Quai-t. .Tourn. Micr. Sci.,' vol. 54. 



