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The ovijeclor. The ovijector (pars houstrix) develops, from the posterior 
end of the genital primordium. Toward the end of the first parasitic stage, and 
especially during the second moult, it can be seen as a cell-group which con¬ 
sists of two to three pairs of cuboidal cells. After the completion of the second 
moult, that is, in the beginning of the second parasitic stage, it can be seen 
as a tube surrounded by two rows of 7 to 8 cuboid cells, which have a size 
of 0-027 to 0-041 by 0-015 to 0-024 mm. (Figs. 26 and 27, oj). In the course 
of the first part of the second parasitic stage the ovijector increases in size, 
measuring 0-08 to 0-1 mm. in length and 0-03 to 0-035 mm. in width. As this 
tube increases in size the cells of its wall become flattened and difficult to see 
and the tube becomes lined with fine longitudinal filaments (Fig. 28, oj, Plate 
XI). Its distal portion at this stage protrudes into the lumen of the vagina like 
a plug (Fig. 28, poj). Toward the end of the second parasitic stage the ovi¬ 
jector increases in length but becomes somewhat constricted and longitudinal 
folds appear along its inside (Fig. 29, oj). At this time a pair of the large cells 
can be seen at the sides of the posterior end of the ovijector (Fig. 30). These 
cells gradually become difficult to see, producing some granules. The structures 
formed from these cells seem to be a fixation apparatus to hold the ovijector 
in that place, since the posterior end of the ovijector is always found on the 
ventral side of the intestine, while all other parts of the internal sex-organs 
remove from the ventral to the dorsal side of the intestine. Therefore the 
ovijector of the adult worm is found to be more or less twisted, crossing the 
posterior part of the intestine. It has a well-developed wall, and has a size 
of 0-1 to 0-13 mm. by 0-025 to 0-03 mm. in living specimens. The wall is 
thickened at the beginning of the ovijector, forming a sphincter, and its 
posterior end projects into the vagina like a plug, forming the second part 
of the ovijector (pars ejectrix of the ovijector). Accordingly the second part 
of the ovijector (Figs. 28-31 , poj) is composed of the distal end of the ovi¬ 
jector and the anterior portion of the vagina. The former is inside and shows 
longitudinal folds, while the latter is outside and is transversely striated. 
(2) The External Sex-Organs. 
General description. The term “external sex-organs” refers to those organs 
which have to do with reproduction in the female but do not develop from the 
genital primordium. They include the posterior part of the ovijector, the 
vagina, and the vulva. 
At the beginning of parasitic life there are many cells in the tail region of 
the female. These cells gradually increase in size and in number with develop¬ 
ment. The majority of these cells are not associated in any demonstrable way 
with the formation of the external sex-organs. In the course of the second 
parasitic stage, they gradually decrease in number and in size. Only the cells 
which are situated on the ventral side just in front of the anus are associated 
with the formation of the external sex-organs. During the second moult these 
cells increase in number and come into contact with the genital primordium 
Parasitology xiv 
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