402 
II. E. Jordan 
considerably, their outline becoming very irregulär and distorted and in 
places having pseudopodia-like projections. f) A delicate faintly-stai- 
ning bridge spans the interval between these processes and the ckromatin 
tliread. Sheppard concludes that, „It may be not at all unlikely that 
by these processes . . . the nncleoli are drawn into the nuclear thread“. 
The association between the granulär nncleoli and the nuclear thread is 
so intimate and the final disappearance of the former is in such a manner, 
„tliat one is led to believe that it is taken up or entirely absorbed by the 
latter“. (p. 553). 
A soinewhat similar chromatic bridge has been described between 
the prematuration chromosomes and the nncleolus in Asterias forbesii'^). 
Again, in Cribrella there is a very intimate relationship between chromo- 
somes and nncleoli as above described. And the same is true of a number 
of other and widely different animal forms. 
Here may be mentioned especially Tubularia Crocea recently des- 
cribed by Hargitt^). As in Cribrella and EcMnaster the chief nncleolus 
in Tubularia fragments into secondary structures some of which „may 
dissolve in the nuclear sap ; others are added to the nuclear reticiüum and 
are apparently transformed into chromatin“ (p. 198). Hargitt thinks it 
possible that, in view of the disappearance of the nncleolus and the for- 
mation of the chromosomes prior to the dissolution of the nuclear mem- 
brane, „the nncleolus may contain something necessary for the formation 
of the chromosomes“ (p. 206). The nucleolar fragments figured for Tu- 
bularia in illustrations no. 45 and 46 resemble very closely similar struc- 
tures pre\dously figured for Echinaster (textfigure 6) ^) and to some extent 
also those here described for Cribrella, and in the three instances, possi- 
bly in very similar manner, contribute to the formation of the prematu- 
ration chromosomes. 
CoMES^) describes very similar phenomena in Serranus scriba (sea- 
bass). Here the chromatin nncleoli of the growdng oöcyte fragment. The 
larger products remaiii scattered peripherally in the germinal vesicle. 
From the smaller fragments (Körnchen) the chromosomes arise. 
From Bigelow’s^) description of the „nuclear cycle of Gonionemus'' 
1) Jordan, H. E. op. cit. 
2) H.argitt, G. T. Maturation, Fertilization and Segmentation of Penmria Tiarella 
(Ajaxes) and of Tubularia Crocea (Ag.). Bull. Mus. Comp. Zool. Harvard Coli. 1909. 
3) Jordan, H. E.‘ op. cit. 
■*) CoMEs, Salv. Sülle relazioni tra vesicola germinative ed ooplasma nell’ oocite 
di Serranus scriba (Cuv.). Anat. Anz. Bd. 28. S. 17 — 24, 83 — 96. 
^) Bigelow, II. B. Studies on the Xuclear Cycle of Gonionemus murbachii. A. 
G. Mayer. Bull. Mus. Comp. Zool. Harvard Coli. 1907. 
