224 TRANSACTIONS OF THE [may 13, 
be regarded as due to faulty preparations, although this ap- 
pears probable in some instances. Fol (’717) was the first 
to note the throwing out of nuclear parts in the eggs of as- 
cidians, observations which he confirmed in ’83 and ’84 on 
the eggs of other forms. According to his view, the nucleus 
gives rise to buds each of which contains a portion of the chro- 
matin network. Balfour (’78) indicated in the eggs of mam- 
mals and elasmobranchs, a mass of granules which he believed 
were detached parts of the nucleolus. Shifer (’80) in the fowl’s 
egg observed that the yolk-nucleus was connected with the ger- 
minal vesicle by numerous fine striations. Balbiani (783) 
claimed that in the Geophilidv it originates by direct transposi- 
tion of parts of the nucleolus of the germinal vesicle. Will 
(784) claimed that in amphibians the entire nucleolus is cast out 
into the cytoplasm. Blochmann (’84) asserted that in hymen- 
optera the germinal vesicle buds, each bud containing some of 
the chromatin network. Scharff (’88) made a similar observa- 
tion on fish eggs. Leydig (’88) saw the nucleolus in triton 
become amoeboid and wander out into the cytoplasm where it 
finally broke up into granules around the periphery of the yolk. 
Van Bambeke (’93) asserted that in the eggs of Scorpena the 
chromatin rods, as such, wander out into the cytoplasm although 
they were seen to undergo no change while there. Finally 
Henneguy (93) and Balbiani (795) found that in various eggs the 
yolk-nucleus originates from the nucleolus. 
It is evident from the foregoing review that not oniy are there 
contradictions in regard to the nuclear or cytoplasmic origin of 
the yolk nucleus, but also that there are various opinions among 
those claiming nuclear origin. Fol (’84), Blochman (784), Scharff 
(788), and Van Bambeke (793) asserted that it is a portion 
or portions of the chromatin network, while Balbiani (’83 and 
93), Will (84), Leydig (’88), ard Henneguy (’93) main- 
tained that it is a portion or the whole of the germinal spot or 
nucleolus. The question of the yolk-nucleus origin stands, 
therefore, in rather an unsatisfactory position. 
The ovary of Lumbricus is small and therefore quite advan- 
tageous for the study of the yolk-nucleus, it being possible to 
eet in one section all of the stages of odgenesis, “from the epi- 
thelial cells at the base of the ovary to the nearly ripe eggs at 
the tip. 
The earliest egg cells (o6gonia) have no indication of a yolk- 
nucleus. They are small and contain large nuclei, the chroma- 
tin being in various stages preparatory to karyokinesis (fig 1.) 
In every ovary, not far distant from the base, there is a more or 
less complete zone composed of cells in the spirem stage of 
———E 
a 
