No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 315 



Scharff ('88) studied the maturation of the eggs of various 

 Teleosts. In the smallest ova examined (.011 mm.) there are 

 numerous peripheral nucleoli, and a few which are central in 

 position. In larger eggs (.03 mm.) " the nucleoli show an 

 inclination to gather still more towards the periphery of the 

 nucleus . . . one or more of the nucleoli become larger than 

 the others, and in their interior refractive specks are visible 

 which have sometimes been described as endonucleoli." In 

 still larger ova (.08 mm.) "in some cases the big nucleoli dis- 

 appear almost completely, leaving an unstained part around 

 them." In Conger \\& "noticed a small nucleolus being con- 

 stricted off from a larger one." He figures outside of the 

 germinal vesicle of Gadus certain granules, and these he 

 considers are emigrated nucleoli which are destined to become 

 dissolved there, though he holds it possible that "some find 

 their way to the surface of the egg to form the nuclei of the 

 follicular epithelium " ; in eggs which have attained the 

 dimensions of .132 mm. the nucleoli become very irregular 

 in shape. In the Trigla egg of .13 mm. the surface of the 

 nucleolus is raised into small protuberances, most of which 

 contain a nucleolus ; these protuberances later break off and 

 become the yolk spherules (in corroboration of Will, '84). 



Schewiakoff ('88), Englypha: the nucleolus gradually dis- 

 appears in the prophasis of mitosis. 



Steinhaus ('88), intestinal cells of Salamandra : karyosomes 

 and plasmosomes are distinguished within the nucleoli, and are 

 usually combined in pairs with one another. Plurinucleolar 

 nucleoli are formed by continued divisions of a single nucleolus, 

 "et les nouveaux nucleoles s'eloignent I'un de I'autre, probable- 

 ment a I'aide de mouvements amoeboides ou d'autres qui leur 

 sont propres." Plasmosomes when extruded into the cytoplasm 

 increase greatly in size, though this increase is due to mere 

 imbibition of some substance ; each such extruded nucleolus, 

 combining with a karyosome, develops into a new nucleus. 



Vejdovsky ('88) studied the maturation of the egg of Rliyn- 

 chelniis. The embryonal genital cells contain no true nucleoli. 

 The nucleolus does not stain when it first appears (in very 

 young stages). Subsequently it is always excentric in position. 



