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has ruptured, the astral rays extend into the cbromosome-mass, and 
the latter breaks up into cbromosomes wbicb as paired rods and ring- 
sbaped bodies become arranged upon tbe spindle. 
Tbe proof tbat tbe mass actually contribntes tbe cbromosomes 
is 1. it can be seen to break up into chromosome-like bodies wbicb 
pass into tbe spindle (Fig. 7); 2. as a small remnant (representing 
several cbromosomes) it is frequently found on tbe spindle togetber 
witb definitive ring-sbaped cbromosomes (Figs. 8 and 9); 3. it can 
never be found after tbe propbase (Fig. 10). Figure 10 represents 
tbe Stage to wbicb maturation proceeds in tbe ovaty. A pause 
tben ensues until spawning and fertilization. Tbe later stages 
including tbe first cleavage are passed tbrougb within an hour after 
fertilization. 
Tbe nucleolus begins to disappear wben tbe cbromosomes pass 
into tbe spindle. Düring later propbase and tbe metapbase stages it 
becomes a pale irregulär body witb cbromatic sbell (Fig. 10) and by 
telopbase it bas become completely resorbed by tbe cytoplasm. Its 
close relation to tbe cbromosome-mass, tbe loss of its cbromatin 
content, its gradual disappearance during metakinesis, and the slight 
increase in size of tbe cbromosomes as they enter tbe spindle and 
for a brief space thereafter indicate a nutritive function i. e. the 
nucleolus appears to be a storehouse for chromatin wbicb is contri- 
buted in part to tbe cbromosomes and in part to tbe nuclear reti- 
culum. The latter as a „residual substance’’ can be recognized as 
late as tbe auapbase wben it becomes indistinguisbable from the gene- 
ral c}'toplasm, and the plastin remnant of tbe original cbromatic nuc- 
leolus also disappears. 
The enlarged cbromosomes of the metapbase stage of the first 
maturation spindle are ver}' cbromatic variously-sbaped structures; 
bipartite rods, crosses, rings, and elongated rods witb terminal knobs 
and median loop or swelling are seen (Figs. 10, 11, 12 and 14). The 
reduced number of cbromosomes is 18 (Figs. 11 and 13). The general 
shape of the cbromosomes is similar to tbat in Zirplmea and Thallasema. 
The cross-forms indicate a double division. Bnt since tbe mode of 
synapsis could not be definitely determined it is quite gratuitous to 
speculate as to wbicb is equational and wbicb is reductional. Figure 15 
illustrates a later anapbass stage; figure 17a sbows an oblique 
cross section of tbe eighteen cbromosomes of the distal pole of this 
stage; and Fig. 17 b, sbows a similar stage of the second maturation 
mitosis. In the early anaphase stages tbere are 18 pairs of cbromo- 
