48 THE HISTORY OF ANIMALS. [_B. III. 



selves, so that unless this membrane is taken away, they all 

 appear to be one passage. These last passages, which are 

 seated upon the testicle, contain sanguineous fluid, but less 

 than those above from the aorta; but in the reflected 

 passages of the duct which is upon the penis, the fluid is 

 white. A passage also leads from the bladder, and is united 

 to the upper part of this duct, which is enclosed in the part 

 called the penis as in a husk. The accompanying diagram 

 will illustrate the position of these parts. 



9. The origin of the passage from the trachea, a ; the head 

 of the testes and the descending passages, b b ; the passages 

 which proceed from these, and are seated upon the testicle, 

 c c ; the reflexed passages which contain the white fluid, 

 dd; the penis, e ; the bladder,/; the testicles, g g. But 

 when the testicles are cut out or otherwise destroyed, the 

 upper passages are retracted ; in young animals castration 

 is performed by bruising the testicles, in older animals by 

 excision. And it has happened that a bull has begotten 

 young if admitted to the female immediately after castra- 

 tion. This is the nature of the testicles of animals. 



10. The uterus of the females that possess this organ is not 

 of the same nature, nor alike in all, but they differ from 

 each other both in viviparous and oviparous animals. The 

 uterus is double in all those animals in which it is situated 

 near the external organ of generation, one part lying on the 

 right side, the other on the left, but the origin is one, and 

 there is but one os uteri, which is like a very fleshy tube, 

 and inmost animals, especially those of a large size, it is 

 cartilaginous. One part of this organ is called the uterus 

 and delphys (whence the word adelphi, brothers), and the 

 vagina and os uteri are called metra. 



11. In all viviparous animals, whether bipeds or quadru- 

 peds, the uterus is placed below the diaphragm, as in the 

 human female, the bitch, sow, mare, and cow, and it is the 

 same in all horned animals. At the extremity of the uterus 

 most animals have a convoluted part called the horns ; these 

 are not distinct in all oviparous animals ; but in some birds 

 they are placed near the diaphragm, and in some fishes 

 below, as in the viviparous bipeds and quadrupeds. But 

 they are thin, membranaceous, and long, so that in very small 

 fish each part of the roe appears as one ovum, as if the fish 



