The relation of nucleoli to chromosomes in the egg of Cribrella sangiiineolenta etc. 403 
one gathers the Impression of a like dose relationship between the nucleoli 
and chi'omosomes. In somatic mitosis the chromatic nucleolar shell is 
said to break down „and contribute its substance to the chromatic struc- 
tures“ (p. 379). — Likewise in the spermatogonial and spermatocyte 
mitoses (nucleolus here a „purely chromatin structure“), „the chromatin 
contributes to the formation of the chromatin net“ (p. 380) . . . „which 
instead of being metamorphosed into a continuous spireme thread, pro- 
bably segments into twenty-four chromatin masses“ (chromosomes). 
And the oögonial mitoses are said to be of the ordinary somatic type. 
The maturation mitoses, however, appear to differ in the matter 
of chromosome formation from the prevaUing condition for Gonionemus. 
In the early prophase stages of the primary oöcytes, the chromatic „nu- 
cleolar Shell breakes down and contributes to the chromatin reticulum. 
The chromatin then condenses into separate ,beaded‘ segments formed 
by the union of varying number of karyosomes. . . . The chromatin seg- 
ments then become irregulär and break down and the nucleus . . . returns 
to a ,resting‘ condition „in which the chromatin is diffused. The central 
portion of the nucleolus persists and develops into the chief nucleolus of 
the growth period of the oöcyte“ (p. 382). In the face of the above facts 
Bigelow asserts that the chief nucleolus „takes no part in the formation 
of the chromatin Strands“ (p. 382) and thus the chromosomes. Moreover, 
he knows „. . . no conclusive evidence that the chief nucleolus in inverte- 
brates ever normally contributes to the formation of the chromosomes 
of the first cleavage spindle“ (p. 367). Such evidence I believe appears 
in the case of Cunina Stschelkanowzew)^), Ästerias, EcJiinaster and 
Cribrella (Jordan) 2) and in Tubularia (Hargitt)^). 
And indeed in the case of Gonionemus it appears more in accordance 
with the facts described to think of the maturation chromosomes as ari- 
sing in part from the nucleolus. For did not the earlier nucleolus contri- 
bute its Shell to the chromatin reticulum from which the chromosomes 
subsequently arise? The so-called „chief nucleolus“ of the full growm 
oöcytes would seem to be more correctly interpreted as the remnant 
(superabundant chromatin) of an original nucleolus w’hose partial func- 
tion was to contribute some substance to chromosomes. Such interpre- 
tation would bring the maturation mitosis as regards the nucleolar- 
chromosome-relationship into harmony with what Bigelow himself de- 
1) Stschelk.cnowzew, J. Die Entstehung von Cunina proloscidea Metschn. 
Mitteil. Zool. Stat. Neap., Bd. 17. 1906. 
2) Jordan, H. E. op. cit. 
3) Hargitt, G. T. op. cit. 
