. Comparative anatomy and physiology. 498 COMPARATIVE ANATOMY AND PHYSIOLOGY. embryonic life, an organ on either side of the heart; and, lastly, it would be as easy to derive the single from the double, as the double from the single arrangement, when we bear in mind that so primitive a form as Peripatus has the two testes completely separated (Fig. 207). jir. Fig. 207.—Male Organs of Peripatus. te, Testes ; vd, vasa deferentia; pr, prostates; p, common duct of vd. (After Balfour.) We find, then, that the generative glands are either distinctly double, united by an obvious bridge, or converted
. Comparative anatomy and physiology. 498 COMPARATIVE ANATOMY AND PHYSIOLOGY. embryonic life, an organ on either side of the heart; and, lastly, it would be as easy to derive the single from the double, as the double from the single arrangement, when we bear in mind that so primitive a form as Peripatus has the two testes completely separated (Fig. 207). jir. Fig. 207.—Male Organs of Peripatus. te, Testes ; vd, vasa deferentia; pr, prostates; p, common duct of vd. (After Balfour.) We find, then, that the generative glands are either distinctly double, united by an obvious bridge, or converted into a more compact single mass, which retains more or less obscurely indications of a primi- tively double arrangement. The male glands are not always rounded off as in the crayfish ; in Squilla they are tubular, and from the sides of the walls short caeca, in which the generative. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bell, F. J. (Francis Jeffrey), 1855-1924. London, Cassell
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