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The inner organisation of the male (Fig. 4) is much the same as that of the
female. Regarding the genital organs we find two ovoid testes (te) in the head,
connected, as is the case with the ovary, by means of a narrow transverse bridge.
The spermaduct (vd) corresponds in shape and course to the oviduct; near the testis
it is a little narrowed but widens soon, keeping the same width to the third thoracic
segment; here it suddenly narrows for again to expand into a sausage-shaped terminal
part, opening with a pore into a space corresponding to the female vagina, lined with
cuticle and covered by the genital opercle.
The peripheral part of the testis contains genital cells, the central part spermatozoa.
The epithelium of the spermaduct is made up of columnar cells with large nuclei,
leaving a narrow lumen; in the terminal part the cavity is wider. In each duct a
spermatophore is formed, consisting of a long thread-like neck, reaching from the
testis till past the constriction, and a sausage-shaped expansion or “receiver”, almost
filling the terminal part. Thus, during copulation, two spermatophores are discharged
at the same time; as already mentioned they may be found adhering to the genital
slits of the female.
The stomach (in) seems more elliptical, the front end as well as the posterior
being narrower than in the female; otherwise the alimentary canal agrees in both
sexes, also as regards the presence of a “stone”. The nervous and the muscular
systems are also alike; only the muscles are stronger and therefore more easily seen.
In the abdomen, however, the median transverse muscles differ considerably: they
are fanshaped, originating widely spread dorsally but inserted as in the female at
the junction of the ventral longitudinal muscles. The paired nature is clearly shown
only by the proximal bundle, and only at their origin.
The stronger development of the muscular system in the male and the more
strongly marked segmentation of its body suggest a greater agility than in the case
of the female; probably it has to leave its own capsule and work its way into that
of the female, with which it wants to copulate and afterwards to stay.
How far the living Chordeuma obesum possesses any colour, I am unable to tell,
as I have only seen specimens preserved for years in spirit. At all events no dark
pigment is found, and the preserved specimens are colourless. As the eggs
sometimes show traces of pink colour, I think they may be more intensely red in the
fresh state and may give a certain amount of colour to the transparent body of the
female.
| II. The development. |
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