454 
MONTGOMERY. 
[Vol. XV. 
Now what do these lightly staining, granular nucleoli repre¬ 
sent ? In all except the seven cases here mentioned the nucleo¬ 
lus was always of the deeply staining, vacuolar type, irrespective 
of its occurrence in ova of egg pouches and of gonophores. 
The abnormal nucleoli, with one exception, were found in the 
largest ova of the egg pouches. Types intermediate between 
the two are represented in Fig. 210. Conklin and Brook’s 
observations, which I can corroborate, show that a number of 
ova are produced in an egg pouch, but that only one of these 
passes into a gonophore, and there develops into the ripe ovum, 
while the others remain behind in the egg pouch and do not 
reach maturity, but degenerate. I would hold that the abnormal 
nucleoli described by me are degenerating nucleoli of degener¬ 
ating ova. All the facts seem to favor such an explanation. 
The cytoplasm of the youngest egg cells appears finely granu¬ 
lar (it may be an alveolar meshwork). In the largest it was 
coarsely vacuolar, especially near the center of the cell; I find 
no evidence of yolk. Conklin and Brooks evidently mistook 
the vacuoles of the cytoplasm for yolk globules. 
No chromatin threads were apparent in the smallest germinal 
vesicles (Figs. 204-206), but only a fine granulation in the 
nuclear sap ; chromatin threads make their appearance gradu¬ 
ally in the larger ova (Figs. 207, 209, 211) and stain more 
intensely as they increase in number and size. Each thread 
often has the form of a chain of transversely placed discs ; or 
sometimes it would seem to consist of a large number of short 
fibrils, placed at right angles to a common longitudinal axis, as 
is the structure of the chromosomes of the Selachian egg. 
These threads usually make their first appearance in the neigh¬ 
borhood of the nucleolus, from which they sometimes radiate 
outwards ; only in the largest nuclei are they more generally 
distributed throughout the nucleus. This fact might show a 
physiological relation between these two structures. But there 
is in all probability no genetic connection between the two ; 
rather, the chromatin threads are built up of the minute micro- 
somes found in the nuclear sap of the smaller ova. But the 
formation of the chromatin threads must be determined by the 
investigator who has more abundant material at his disposal, 
