. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE GENITAL ORGANS OF THE MALE. flattened, or lancet-shaped head, and a filiform tail terminating in a point ; this tail is often furnished at its origin with an enlargement, or unilateral or bilateral alae. Their form is slightly modified during their course through the excretory ducts. (In the different species, though possessing certain fixed characters, the spermatozoa yet offer some curious diversities. Some of these are well exhibited in the annexed representations of these particles, found in the semen Fig. 521.
. The comparative anatomy of the domesticated animals. Veterinary anatomy. THE GENITAL ORGANS OF THE MALE. flattened, or lancet-shaped head, and a filiform tail terminating in a point ; this tail is often furnished at its origin with an enlargement, or unilateral or bilateral alae. Their form is slightly modified during their course through the excretory ducts. (In the different species, though possessing certain fixed characters, the spermatozoa yet offer some curious diversities. Some of these are well exhibited in the annexed representations of these particles, found in the semen Fig. 521. of very dissimilar animals.) The spermatozoa move by undu- lations of the tail (Grohe attributes the motion to the contractile pro- toplasm contained in the head) ; ihey can traverse '004 m. in a minute. Their movements persist for several days in the genital organs of the female ; they are suddenly arrested by water, acids, and the electric spark ; on the contrary, they are animated by alkaline fluids. (The movements cease when the spermatozoa are ex- posed to a temperature of 120° Fahrenheit.) These bodies are de- veloped in the cells of the tubuli seminiferi by a modification of their contents. Their development has been already described 1, Spermatozoon of the fro^; 2, of the triton ; 3, of the finch; 4, of the field-mouse; 5, of the hedge- hog ; 6, sheep, a, Head with nucleus ; b, body ; e, tail. Excretory Apparatus of the Semen. 1. The Epididymis and Deferent Canal (Figs. 368, 517, 518, 519). Epididymis.—The organ thus named commences the excretory canal of the testicle. It is a body elongated from before to behind, placed against the upper border, and a little to the outside, of the testicle. It has a middle portion and two extremities. The middle is contracted, flat on both sides, and free outwardly ; it is related, inwardly, to the spermatic vessels and the testicle, to which it is attached by a very short serous layer. The extremities are expanded, and adhe
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