. The comparative anatomy of the domesticated animals. Veterinary anatomy. 874 THE GENERATIVE APPARATUS. Fig. 407. veins are of large calibre, and form a very rich network around the gland -—the bulb of the ovary ; they terminate in the vena cava, near the renal veins. The lympyiatks pass to the sublumbar glands. The nerves emanate from the small mesenteric plexus. Development.—The ovary of Solipeds is of great size in the foetus, being often nearly as large as in the adult animal. It becomes wasted in aged animals. Functions.—The productive organs of the germ or ovum, the ovaries are the test
. The comparative anatomy of the domesticated animals. Veterinary anatomy. 874 THE GENERATIVE APPARATUS. Fig. 407. veins are of large calibre, and form a very rich network around the gland -—the bulb of the ovary ; they terminate in the vena cava, near the renal veins. The lympyiatks pass to the sublumbar glands. The nerves emanate from the small mesenteric plexus. Development.—The ovary of Solipeds is of great size in the foetus, being often nearly as large as in the adult animal. It becomes wasted in aged animals. Functions.—The productive organs of the germ or ovum, the ovaries are the testicles of the female. They form the ovulum, and then at a cer- tain period set it at liberty. As the ovulae are contained in the ovisacs, it is necessary to study: i, The development of these ovisacs; 2, Their rupture or dehisence; 3, The phenomena occuriug in them after this rupture. Development of the Ovisacs.—The ovisacs already exist in the ovary of the foetus and the young animal, but only assume their greatest activity at the age of puberty. They are not all formed at birth, but are incessantly re-developed, this development taking place beneath the tunica albuginea. (At puberty, the stroma of the ovary is crowded with ovisacs so minute, that in the Cow it has been computed that a cubic inch would contain two hundred millions of them.) At first the ovisac consists of a small cell, which presents all the constituent parts of the ovulum. As it becomes developed it sinks into the cortical layer, being pushed deeper into it by the cells that grow outside it; and it is also surrounded by a granular membrane, formed at the expense of the nuclear elements of the adjacent connective tissue. This membrane soon separates at a given point into two layers, to form a cavity that gradually extends and becomes filled with fluid : this is the cavity of the ovulum. As the separation is not complete, tlie ovulum, enveloped by the internal granular membrane, remains beside the extern
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