DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
571 
and vagina (fig. 92 a, h,f, g) is dependent on the eggs with which they are distended, 
while the transparent portion (fig. 92 c, d) contains hardly any (fig. 90 c, d). 
This part has not received any definite name, nor have its limits been pointed out ; 
but as it is here that the important process of fecundation takes place a name be- 
comes indispensably necessary. To this, therefore, I shall apply the name of Oviduct 
(figs. 90 and 92 c, d). 
The upper extremity of the ovary is formed of a membranous and perfectly trans- 
parent tube (Plate XXVII. fig. 39 h), much thicker at the very end (fig. 39 a). It is 
from this thick portion (fig. 39 a), which presents a finely granular structure, that 
the germinal vesicles are thrown off ; it constitutes therefore the true ovary. 
A short distance from the extremity, one or more apparent invaginations occur 
(fig. 39 h, h), as if other caecal tubes were contained within the first ; but these appear- 
ances are probably caused by casts of the internal surface of the upper end of the 
ovary (fig. 39 a), which are probably thrown off at intervals. 
On examining a portion of the ovarian tube where it begins to be opake (fig. 40 h), 
we observe it marked with very faint lines and minute granules ; but as we descend 
they gradually increase in distinctness. The sides also become thicker, so that about 
midway the tube is formed of a homogeneous membrane externally (fig. 41 A), con- 
tinuous with that forming the caecal extremity (fig. 39 h), and a number of longi- 
tudinal ridges or striae internally (fig. 41 /). Each of these longitudinal striae 
(fig. 41 /) contains a number of granules imbedded in them, causing them to project 
into the interior of the tube, and giving it somewhat the appearance of a rifle barrel 
(fig. 41 k). 
This is the structure presented by the ovarian tube for the greater part of its length 
(fig. 41), commencing as soon as granules are seen to surround the germinal vesicles 
(fig. 40 k), and becoming gradually more distinct to within a short distance of the ovi- 
duct, where the striae disappear and the external membrane alone remains (fig. 42 A). 
The spot where the ovary terminates and the oviduct (fig. 42 m) begins is marked, 
as already stated, by a constriction (Plate XXX. fig. 90 c), causing such an amount 
of narrowing in the calibre of the generative tube (Plate XXVII. fig. 42 m) as only to 
admit the passage of one ovule at a time (fig. 42 o). The whole length of the ovi- 
duct (Plate XXX. fig. 90 c, c?) is characterized by transverse markings, evidently of 
a muscular or contractile nature, and most developed at the ends where the constric- 
tions (Plate XXVII. fig. 42 m) occur. While the exterior of the oviduct is trans- 
versely ribbed (fig. 42 n), its interior is lined with large cells, distended with a dark 
granular fluid, projecting into the cavity of the tube, and having all the appearance of 
.seereting cells. 
That these cells do secrete some sort of fluid, is proved by the fact that they 
become turgid when the Ascaris has been feeding, and are, on the contrary, almost 
invisible from flaccidity when it has had no food. 
While the ovary is filled with an almost solid mass of ovules (Plate XXX. fig. 90 h), 
MDCCCLIl. 4 E 
