Volume //.] June, lyoi. \_No. 6. 



BIOLOGICAL BULLETIN. 



[From the Zoological Laboratory of the University of Pennsylvania.] 



THE INDIVIDUALITY OF THE GERM NUCLEI 



ERRATA. 



In No. 5, p. 225, igth line, read sensory bulbs in place of 

 tentaculocysts. 



On p. 228, 2oth line, read ocelli in place of otocysts. 



.ioi. null. 



ot other animals. 1 







1 Riickert calls attention to the fact that partially cleft nuclei are found in 

 the figures of various authors, particularly those of Fol ('79) on Toxopneustes, 

 of Bellonci ('84), and of Kolliker ('89) on Siredon. Of course no one of these 

 observers has interpreted these figures as showing the independence of the germ 

 nuclei, and some of the figures referred to by Riickert probably do not show this 

 phenomenon. For example, only one of Fol's figures (PI. VII, Fig. 7) shows a 

 dual nucleus, while the figure in Kolliker's text-book (Fig. 36) is probably a case 

 of the indentation of the nuclear membrane opposite the centrosomes in the early 

 prophase, a thing which frequently happens. Bellonci's Figs, i and 20 show an 

 indentation on one side of the nucleus which may correspond to a division between 

 the germ halves, though this must be regarded as more or less doubtful. 



257 



