. The Cambridge natural history. Zoology. 140 MALE-STRUCTURES of testes, organs exhibiting much variety of form. The structure may consist of an -ex'tremely long and fine convoluted tube, packed into a small space and covered with a capsule; or there may be several shorter tubes. As another extreme may be mentioned the existence of a number of small follicles opening into a common tube, several of these small bodies forming together a testis. As a rule each testis has its own capsiile, but cases occur—very frequently in the Lepidoptera—in which the two testes are enclosed in a common capsule;
. The Cambridge natural history. Zoology. 140 MALE-STRUCTURES of testes, organs exhibiting much variety of form. The structure may consist of an -ex'tremely long and fine convoluted tube, packed into a small space and covered with a capsule; or there may be several shorter tubes. As another extreme may be mentioned the existence of a number of small follicles opening into a common tube, several of these small bodies forming together a testis. As a rule each testis has its own capsiile, but cases occur—very frequently in the Lepidoptera—in which the two testes are enclosed in a common capsule; so that there then appears to be only one testis. The secretion of each testis is conveyed out- wards by means of a slender tube, the vas deferens, and there are always two such tubes, even when the two testes are placed in one capsule. The vasa deferentia differ greatly in their length in different Insects, and are in some cases many times the length of the body; they open into a common duct, the ductus ejaculatorius. Usually at some part of the vas deferens there exists a reservoir in the form of a sac or dilata- tion, called the vesicula seminalis. There are in the male, as well as in the female, frequently diverticula, or glands, in connexion with the sexual passages; these sometimes exhibit very remarkable forms, as in the common cockroach, but their functions are quite obscure. There is, as we have already remarked, extreme variety in the details of the structure of the internal reproductive apparatus in the male, and there are a few cases in which the vasa deferentia do not unite behind, but terminate in a pair of separate orifices, the form of the sexual male as we have already mentioned it to be in the corresponding parts of the female. Although the internal sexual organs are only fully developed in the imago or terminal stage of the individual life, yet in reality their rudi- ments appear very early, and may be detected from the embryo state onwards through the ot
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
