THE HORSE. 



IT 



" Now in all fatty bodies there are con- 

 tained, on an average : 



" For 120 eq. carbon, only 10 eq. oxygen. 



" Since the carbon of the fatty constit- 

 uents of the animal body is derived from 

 the food, seeing that there is no other 

 source from whence it can be derived, it is 

 obvious, if we suppose fat to be formed 

 from albumen, fibrine, or casein, that for 

 every 120 equivalents of carbon deposited 

 as fat, 26 equivalents of oxygen must be 

 separated from the elements of these sub- 

 stances ; and, further, if we conceive fat to 

 be formed firom starch, sugar, or sugar of 

 milk, that for the same amount of carbon 

 there must be separated 90, 100, and 110 

 equivalents of oxygen from these com- 

 pounds respectively. 



" There is therefore but one way in which 

 the formation of fat in the animal body is 

 possible, and this is absolutely the same in 

 which its formation in plants takes place ; 



it is a separation of oxygen from the ele- 

 ments of food." 



OF THE EXTERNAL PARTS. 



THE HOOF.* 



" The hoof is the horny case or covering 

 nature has provided for the protection of 

 the sensitive parts of the foot. It may be 

 said of itself to constitute such a shoe or 

 defence, as enables the animal in his wild 

 state to travel about in quest of food, not 

 only without injury to the structures under- 

 neath it, but with a degree of elasticity that 

 preserves his whole frame from concussion. 

 Were one forced into any comparison of 

 the sort, it must be admitted that the hoofs 

 of animals bear some anatomical affinity 

 to the human nails, or claws, of other 

 animals ; though they are vastly superior 

 in physiological importance to any such 

 appendages as these. 



* Percivall's Anatomy. 



EXAMINATIONS RESUMED. 



ADIPOSE TISSUE. 



Q. What IS the fatty matter contained in the adiijose 

 cells composed of? — A. Steariue, margarine, and 

 oleine. 



Q. How do they appear when isolated? — A. The 

 two former are solid, and the latter is fluid. 



Q. How are they preserved in a fluid state in the 

 animal body ? — A. By the ordinary^ temperature of 

 the body. 



Q. What are the observable differences in color 

 occurring in different jiarts of the body, and in animals 

 of diverse temperaments ? — A. In some parts of the 

 body it is white, in others it has a yellow tinge ; in 

 animals of lymphatic and nervous temperaments it is 

 wliite; in the sanguine it has somewhat of a red 

 tinge ; in the bilious, it presents a yellow appearance. 



Q. The fat at the ordinary temperatm-e of the li\-ing 

 body being fluid, how is it retained m the fat cells with- 

 out transudation ? — A. The intervals of the fat cells 

 are traversed by a minute net-work of blood A'essels, 

 from which they derive their secretion ; and it is prob- 

 ably by the constant moistening of their walls with a 

 watery fluid, that their contents are retained. 



Q. What are uses of the adipose tissue? — A. It is 

 intended to fill up spaces ; forms a sort of cusliion or 

 pad for the support of movable parts. It also acts as 

 a non-conductor of heat, thus preser\ing the animal 

 temperature; it serves as a reservoir of combustible 

 3 



matter, at the expense of which the respiration may be 

 maintained when other materials are deficient. 

 i Q. Suppose you desired to fatten a horse or an ox, 

 what method should you adopt ? * — A. I should keep 

 the animal at rest, and furnish him with an abundance 

 of nitrogenized food. 



Q. In what vegetable constituents does nitrogen 

 abound ? — A. In vegetable fibrine, albumen, and 

 caseine. 



* Experience teaches us that, in poiiltry, the maximum of fat is 

 obtained by tying the feet, and by a medium temperature. These 

 animals in such circumstances may be compared to a plant possessing 

 in the highest degree the power of converting all the food into parts of 

 its own structure. The excess of the constituents of blood forms 

 flesh and other organized tissues, while that of starch, sugar, etc., is 

 converted into fat. When animals are fattened on food destitute of 

 nitrogen, only certain parts of their structure increase in size. Thus, 

 in a goose, fattened in the method above alluded to, the liver becomes 

 three or four times larger than in the same animal, when well fed 

 with free motion, while we cannot say that the organized structure 

 of the liver is thereby increased. The Uver of a goose fed in the 

 ordinary way is firm and elastic ; that of the imprisoned animal is 

 soft and spongy. The difference consists in a greater or less expan- 

 sion of its cells which are filled with fat. 



In some diseases, the starch, sugar, etc., of the food obviously do not 

 undergo the changes which enable them to assist in respiration, and 

 consequently to be converted into fat. Thus, in diabetes melUtua, 

 the starch is only converted into grape sugar, which is expelled 

 from the body without further change. 



In other diseases, as for example in inflammation of the liver, we 

 find the blood loaded with fat and oil ; and in the composition of the 

 bile there is nothing at all inconsistent with the supposition that 

 some of its constituents may be transformed into fat. 



