No. 2.] THE DEVELOPMENT OF THE NEWT. 297 



young eggs somewhat surpass in size those in slightly advanced 

 stages. I have not found this to be the case in Dicmyctylus 

 In a germinal vesicle some 6o/a in diameter and containing 199 

 nucleoli, the larger nucleoli measured from i^ to 3/x,, the latter 

 dimension being never exceeded. A germinal vesicle about 

 90ya in diameter contained about 442 nucleoli, the larger of 

 which measured 3/a to 4;a, while another vesicle 13 i/x in diameter 

 contained 1123 nucleoli of about ^^l. The preponderance of 

 large nucleoli is, if anywhere, on the side of the large eggs. 

 Furthermore, if multiplication of the nucleoli by division were 

 the ordinary occurrence, we might expect to find a certain 

 uniformity in the size of these bodies, and a certain critical 

 bulk, so to speak, at which division takes place. This is not so, 

 but on the contrary, the nucleoli attain their maximum size 

 shortly before their centripetal movement, which is just the 

 condition that might be anticipated if we assumed a steady 

 development and growth from the beginning. It is, moreover, 

 not difficult, particularly in the early stages, when the number 

 of nucleoli increases most rapidly, to find all gradations from 

 the largest to the smallest, the smallest being indistinguishable 

 from the more conspicuous granules in the threads. These 

 facts would lead to the suspicion that the origin of the nucleoli 

 is in some way intimately associated with the chromatin 

 threads, that in fact the larger granules of the threads, such as 

 seen in Fig. 14, break loose from the threads and pass over into 

 true nucleoli. I incline to believe that such is the case. 

 Leydig ('88) holds a similar view as to the origin of the nucleoli 

 in Triton taeniatiis : "... in der Mitte des Keimblaschens 

 ein zartes, dichtes Reticulum sichtbar ist, dessen Knotenpunkte 

 von Keimflecken der kleinsten Form nicht zu unterscheiden 

 sind, so dass ein Uebergang der einen in die andern unmoglich 

 geleugnet werden kann (Fig. 94)." If the nucleoli in the 

 growing egg thus arise from chromatin threads, it strengthens 

 the probability of a like origin for the first-born nucleoli. 



Nucleoli are often said to arise as " much-thickened knots of 

 the network of threads." I cannot regard such an expression 

 as appropriate in the present instance, since there is no true 

 "network," and since the designation of the young nucleolus 



