1886.] OVUM OF LEPIDOSIREN. 277 
membrane of the germinal vesicle is not always very obvious ; 
but as-there is a sharp contrast between the protoplasm of the 
germinal vesicle and the surrounding substance of the ovum (indi- 
cated by the much deeper staining of the former by borax carmine), 
there comes to be an appearance of a delicate membrane surrounding 
the germinal vesicle ; this membrane has not a double contour. 
In younger ova there is a very distinct membrane bounding the 
germinal vesicle externally ; this membrane is more easily to be 
distinguished in my preparations from the fact that it is very deeply 
stained. 
Although the boundaries of the germinal vesicle are distinct 
enough, there is no cavity dividing it from the egg-protoplasm ; the 
granules of the latter are everywhere in contact with the germinal 
vesicle. In several preparations the germinal vesicle had shrunk ; 
but in every case observed by me the wall of the germinal vesicle 
was covered with egg-protoplasm granules, thus showing that the 
spaces surrounding the germinal vesicle in that figure are not 
natural, but due to alterations caused by the contraction of the ger- 
minal vesicle. 
The interior of the germinal vesicle is occupied by a finely- 
granular matter, which is almost homogeneous throughout. In 
certain tracts, however, the granules are more deeply stained and 
often larger; these granules form a reticulum (Plate XXIX. fig. 3). 
In the ovum of Triton, Iwakawa illustrates (loc. cit. pl. xxiv. fig. 27) 
a very similar condition of the nucleoplasm. The germinal spots 
are very numerous, and form a layer surrounding the germinal 
vesicle ; the latter is shown on a superficial view in fig. 3, and in 
transverse section in Plate XXIX. fig. 4. The germinal spots are 
of very varying size, and usually oval or circular in form ; borax 
carmine stains them more deeply than the surrounding nucleoplasm ; 
they are evidently not homogeneous, but appear to consist of an 
outer sheath of stout consistency, and very deeply stained by the 
reagent, and within this an apparently more fluid core which is not 
deeply stained. 
The presence of numerous germinal spots is figured by Ayers 
for both Ceratodus (plate xviii. fig. 76) and Lepidosiren (plate xvii. 
fig. 27). 
It is also characteristic of the Teleostean ovum *, and is mentioned 
by Messrs. Balfour and Parker * in Lepidosteus. Among Amphibia 
Triton shows the same condition of the germinal spots. In ova of 
the stage represented in Plate XXVIII. fig. 2, the substance of the 
ovum which immediately surrounds the germinal vesicle differs from 
the rest in being more loosely compacted. 
In ova which are distinguished by the enormously increased 
functional activity of the follicular epithelium, the germinal vesicle 
could not be found. In all probability, however, my failure to find 
the germinal vesicle is not due to its absence. 
* Brock, “ Beitrage z. Anatomie und Histologie der Geschlechtsorgane der 
Knochenfische,” Morphol. Jahrb. Bd. iv. (1878) p. 505, pl. xxviii. figs. 8, 11. 
* “On the Anatomy and Development of Lepidosteus,” Phil. Trans. 1884. 
