No. 2] | THE OOGENESIS OF BUFO LENTIGINOSUS. 419 
but little morphological value to the rounded granular ball 
which he finds in the cytoplasm of the egg of Rana. “Mir 
scheint er einzig and allein mit der Bildung der Dottersubstanz 
in Beziehung zu stehen und eine eigenthtimliche locale An- 
sammlung von Nahrstoffen darzustellen.” He suggests that 
the name “Dotterconcrement” would be more appropriate for 
this structure than “Dotterkern.” Kolessnikow (55) men- 
tions the presence of granular yolk-nuclei in the eggs of Rana 
temporaria, Rana esculenta, and Bufo variabilis, but he gives 
no opinion as to their origin or use. 
Henneguy (38) finds a large granular mass, presumably a 
yolk-nucleus, in the egg of Rana, although he fails to find a 
similar body in the egg of Bufo vulgaris, Triton teeniatus, and 
Triton cristatus. Henneguy believes that wherever this body 
is found it is derived from the nucleolar substance of the 
nucleus and he ventures the interesting conjecture that “c’est 
un organe ancestral qui, avec les éléments nucléolaires de la 
vesicule germinative, correspond au macronucléus des In- 
fusoires, le micronucléus étant représenté par le rdseau chro- 
matique, prenant seul part aux phénoménes de fécondation.” 
Jordan finds a number of granular yolk-nuclei in the egg 
of the newt which he believes “arise from the cytoplasm and 
usually disintegrate in the cytoplasm.” He is not sure whether 
these structures are of importance in the formation of yolk 
or not. Jordan’s observations regarding the fate of these yolk- 
nuclei will be mentioned later. 
The observations of several investigators seem to show that 
nuclear substance is used in the formation of yolk. In 1884, 
Will brought forward the view that in the ova of amphibians 
and of insects nucleoli leave the nucleus and migrate to the 
periphery of the egg where, as yolk-nuclei, they lose their 
sharp contour and break up into granules which become yolk 
spherules. Substantially the same view was advanced by 
Leydig in 1888 to account for the origin of the yolk in the 
egg of Triton. Leydig considers that the nucleolj arise in 
the nucleus “als Knotenpunkte in dem feinen Netz des Re- 
ticulums,” and that they move to the periphery of the nucleus 
