36 INTRODUCTION. 



canal or tube, conducting to an oval body of the size of an egg, con- 

 tainino; numerous little vesicles or bladders called ova, or eggs ; and 

 the collection of them is denominated the ovaries. At the time of 

 conception one of these ova escapes, and slowly descends the tube 

 and enters the womb. It is the germ of the future animal, but scarcely 

 larijer than a pea. Arrived in the womb it floats there for a while, 

 and at length becomes attached to some portion of it. When it de- 

 scended it was enveloped by two membranes or coats, and two others 

 now rapidly form over it from the uterus. They are exceedingly 

 vascular, and by means of them, and the vessels proceeding from 

 them, not only is nourishment conveyed to the foetus, but the blood 

 which has circulated through its little frame is purified. 



At the fourth week it has attained the size of a mouse, and every 

 limb is to be seen nearly perfect, although in miniature. It has eyes, 

 although at present it sees not, and a mouth, but no food enters it : 

 the lungs perform no office, and the stomach receives no nourish- 

 ment ; but the blood of the mother is sufficient for its nutriment and 

 its growth. 



In the cow and other ruminant animals there are a vast number of 

 red prominences between the membranes, consisting of thousands of 

 convolutions and ramifications of blood-vessels : they were designed, 

 probably, more completely to purify the blood, and render it more fit 

 for the nourishment and rapid growth of the quadrupeds that are des- 

 tined to contribute to the food of man. 



In the fourth month the foetal calf is large, but the skin is not 

 covered with hair. About the sixth or seventh month the hair has 

 spread over it, and at the expiration of nine months the animal is 

 sufficiently well formed and strong to change its mode of existence. 

 The womb has now attained its greatest degree of distention : it be- 

 comes irritated; its muscular fibres begin to contract; labour comes 

 on, and, assisted by the diaphragm and abdominal muscles, the calf 

 and its menibranes'are expelled, and the young animal is born. 



As the pelvis, from its horizontal position, may safely be much 

 larger in these animals than in the human female, parturition is, 

 generally speaking, not dangerous or very painful in the quadruped. 

 Difficult labours, however, and false presentations will sometimes 

 occur, of which nntiee will be taken in the proper place. 



T/te Udder. — The udder is a large glandular organ, destined to 

 secrete milk for the nourishment of the young calf. As the produce 

 of the cow is confined to one, or at most to two calves at a birth, the 

 udder would perhaps have been only double, as in the mare, were it 

 not that this animal is intended to yield the greater part of her milk 

 for the nourishment of man. The bag is therefore quadruple, or there 

 are four distinct partitions of it. 



The udder is made up of numerous minute branches of arteries, 

 from the extremities of which the milk is secreted. This secretion is 

 always goinir on. The bag of a milch cow is always gradually filling, 

 yet a considerable proportion of that which is given is secreted at the 



