326 MONTGOMERY. [Vol. XV. 



nucleolus breaks into a number of nucleoli of various sizes. 

 After the copulation and encysting the nucleoli fuse together 

 and gradually disappear (but I am unable to determine from 

 his description whether the substance of the chromosomes is 

 derived from the nucleoli). Shortly after the nuclei themselves 

 copulate, the nucleoli reappear in them. In Clcpsidrina blat- 

 tariwi there is a single primitive nucleolus, formed as in 

 the preceding species ; later there are numerous smaller 

 nucleoli, which have probably arisen by division from the 

 primitive nucleolus. 



i8g2. 



Bannwarth ('92) figures a division of the nucleolus in leuco- 

 cytes from the spleen of the cat. 



Born ('92) finds that in the Amphibian egg, in opposition 

 to the observations of O. Schultze ('87), the chromatic "Faden- 

 knauel " has no origin in the nucleoli, but is directly derived 

 from the chromatin network of the " Urei." 



Brauer ('92) made observations on the maturation and fecun- 

 dation of the egg of Branc/iipus. Each germinal vesicle from 

 the " Wachsthumszone " of the ovary has one large, slightly 

 staining nucleolus, and near it a much smaller, deeply staining 

 one. Each " Nahrzelle," however, contains numerous nucleoli, 

 and its nuclear sap also stains deeply. When the chromosomes 

 are being produced, the larger nucleolus of the egg cell gradu- 

 ally ceases to stain, and it finally disappears. In the male 

 pronucleus small nucleoli are present. 



Frenzel ('92) noticed in Carcinus moenas and in a species of 

 Amphipod, in the ferment cells and " Fettzellen " of the hepa- 

 topancreas, amitotic division of the nucleus, but no division of 

 the nucleolus ; " sondern dass vielmehr an geeigneter Stella 

 des Tochterkernes noch vor der Abschniirung desselben ein 

 ganz neuer Nucleolus entstehe, der alle Charaktere des ersten 

 besitzt " ; in this nuclear division one of the daughter-nuclei 

 retains the whole original nucleolus. In similar cells of Idotea 

 tricnspidata he found the nuclear division to be as in the pre- 

 ceding species (but his Figures 8b, lo, and especially ii, would 

 seem to represent stages of division of the nucleolus). 



