DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
573 
tact, though not adherent to the germinal vesicles (figs. 39, AO d). A little further 
down we observe the whole contents of the tubes to become gelatinous, and to con- 
sist apparently of nothing but granules. On applying gentle pressure so as to rup- 
ture this portion of the tube, the granular contents are easily forced out and may be 
seen to break up into semitransparent masses (figs. 45, 46). 
Each mass (figs. 45, 46 d) constitutes an ovule, small and imperfect, but contain- 
ing all the parts essential to an ovule. In the centre of each is a germinal vesicle 
(figs. 45, AQb) enclosing a germinal spot (figs. 45, 46«), and surrounded by opake 
granules (figs. 45, 46 c) imbedded in a transparent jelly-like substance. 
These granules (figs. 45, 46 c) are of a fatty nature, and constitute the yolk in its 
primitive condition. 
The ovule in this stage of its dev^elopinent is very irregular in form (figs. 45, 46), 
sometimes caudate, sometimes triangular, and at others round. They are all flattened 
and transparent, so that the contained germinal vesicle and spot may be distinctly 
recognised (figs. 45, 46 a, b) when viewed separately. 
The distinctness of the outline which the transparent substance of the ovule pre- 
sents (figs. 45, 46 d), led me at first to suppose that it was caused by a delicate enve- 
loping membrane ; but from further research I am led to believe that no such mem- 
brane exists, but that the distinct and regular outline is owing to the solidity and 
high refractive power of the clear substance (figs. 45,46 c?). 
When the ovule is of a caudate or triangular form (fig. 45 d), the clear substance 
does not present so distinct an outline at the apex as elsewhere. From its being in- 
variably placed nearest the centre of the ovarian tube it is probably the last formed, 
and therefore less consolidated than the other parts. It is doubtful whence the vitel- 
line granules are formed (figs. 45, 46 c); they may be either thrown off by the csecal 
extremity along with the germinal particles, separate spontaneously from the sur- 
rounding fluid, or be formed by the striated walls of the ovary. 
I believe that the large granules (fig. 39 g), first seen to surround the germinal 
vesicles, are thrown off by the blind extremity, and become attached to them by 
the coagulation, or rather the consolidation of the surrounding albuminous fluid 
(figs. 45,46). But when the ovule arrives at the striated portion (fig. 41) the 
number of yolk-granules is greatly increased (Plate XXVIII. figs. 48, 51 c), leading 
to the supposition that the granules contained within the strim (Plate XXVII. 
fig. 41 h) are thrown off, and become imbedded in the clear substance of the ovule 
(Plate XXVIII. figs. 48,51 d). 
The possibility of such an occurrence cannot be doubted, both from the absence 
of a distinct limiting membrane round the ovule, as well as from the gelatinous na- 
ture of the clear substance, having a tendency to entangle and detain anything that 
may come in contact with it. 
The germinal vesicles maintain exactly the same appearance, but increase a little 
in size (fig. 48 6), become globular in shape, and contain a highly refractive fluid 
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