No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 451 
formation and fuse with the former. Were these secondary 
nucleolar globules in Lineus as large as the first-formed 
nucleolus, and were they all to remain separate from one 
another, the nucleolar metamorphosis in this genus would 
correspond to that of the metanemerteans ; accordingly, the 
difference in the nucleolar production is not very important. 
(For the nucleolar relations in the other nemerteans, cf. my 
reviews of the papers of v. Kennel, Hubrecht, Coe and Burger. 1 ) 
9. Siphonophore (Rodalia .?). 
(Plate 26, Figs. 204-212.) 
(Dr. Conklin kindly loaned me the preparations on which his 
earlier studies were based (’ 91 ); these were preserved in alcohol 
and stained with haematoxylin.) 
There were no very young stages of the ovogenesis in this 
specimen ; I have studied the ova in the egg pouches and in 
the gonophores, each gonophore containing a single large ovum 
(as shown by Conklin and Brooks), while in the egg pouches a 
number of smaller ova may be present. 
A single large nucleolus is contained in each germinal 
vesicle. This is not only large in relation to the size of the 
nucleus, but is also absolutely probably one of the largest 
nucleoli ever described in animal cells (Fig. 212). It is always 
excentric in position, though seldom close to the nuclear mem¬ 
brane. In those younger stages where the nucleus is still near 
the center of the egg (Fig. 205, and the dorsal cell of Fig. 211) 
1 The only other observations of the yolk development in the nemerteans are 
those of Burger (’ 90 ) on Drepanophorus. Near the young germinal vesicle lies in 
the cytoplasm a homogeneous, deeply staining body, of smaller size than the 
nucleus, which Burger assumes may correspond to a yolk nucleus. This body 
disappears, “ und es sammeln sich namlich, dem Keimblaschen anliegend, in jenem 
[Plasmahiigel] kuglige oder langliche, tropfchenahnliche Gebilde an, erst sp'arlich 
ein einziges, zwei und mehrere, spater aber mit dem immer noch fortschreitenden 
Wachstum des Keimblaschens sich zahlreich vermehrend in grosster Menge. Sie 
sind durchaus homogen, von mattem Glanze und ausserst tinktionsfahig. . . . 
Erst nach der Entwicklung des Keimblaschens geht die des Deutoplasm as vor 
sich und zwar nun auf Kosten der glanzenden Dotterballen, welche aufgebraucht 
werden und so im reifen Ei verschwinden.” In the ripe egg the cytoplasm is 
granular and stains lightly. 
