464 
MONTGOMERY. 
[Vol. XV. 
this substance would superinduce the lilac staining of the 
chromatin threads. This addition of a probably nutritive 
substance would seem necessary, in order that the amount of 
the chromatin continue to increase as the nucleus itself grows 
larger. Subsequently all that nutritive substance attached to 
the chromatin threads would seem to become metamorphosed 
into chromatin, since in the largest germinal vesicles these 
threads again stain a deep blue. And as a matter of fact, the 
quantity of the chromatin must increase with the growth of the 
ovum, since it can easily be demonstrated that in the larger 
nuclei there is an absolutely greater amount of this chromatin 
present than in the nuclei of the primitive peritoneal cells. 1 
ii. Piscicola rapax (Verr.) (= Pontobdella rapax Verr., which 
Dr. Percy J. Moore assures me is a true Piscicola). 
(Plate 29 , Figs. 300 - 316 .) 
(The ovary is a tubular, contorted sack; from its inner sur¬ 
face numerous smaller, likewise tubular (round on cross-section), 
acini project into its cavity, each acinus containing numerous 
ovogenetic stages, the least mature of which lie at its proximal 
end, the most mature at its distal. These several acini are 
not continued as far as the external opening of the ovary, but 
their distal ends apparently open into a large ovarial cavity, 
and the ova drop into this cavity before they can arrive at the 
external genital opening. Each single acinus of this leech may 
be compared to either of the two whole ovaries of Ascaris.) 
The youngest ovarial stages are small ovogonia in stages of 
mitotic division (Fig. 300). In them no nucleoli were to be 
seen; a minute nucleolus might be present in each of these 
nuclei and be obscured by the dense mass of chromatin. In 
all stages subsequent to these a single nucleolus is present in 
the nucleus (now a germinal vesicle) until the pole spindle is 
formed; in the smaller nuclei the nucleolus is usually oval, in 
the larger ones spherical. The growth of the nucleolus keeps 
1 For the researches of other authors on germinal spots of polychaetous anne¬ 
lids, cf. the reviews of the papers of Korschelt (’89, ’95), Graff (’88), Giard (’81), 
Vejdovsky (’82), Eisig (’87), Fraipont (’87), Mead (’95), Fauvel (’97), Michel 
(’96), and Carnoy (’84). 
