102 Anatomy and Physiology of the Mammary Gla)id. 



Avith the carbon and hydrosen of the system, and the consequent 

 production of carbonic acid gas and watery vapour, which takes 

 place in the capillary vessels of the entire organism, that animal 

 heat is produced. The carbon and hydrogen are thus being 

 constantly consumed, and to supply their place the hydro-car- 

 bonaceous materials of the body are appropriated. By the process 

 of respiration oxygen enters the system ; and by the same process 

 the carbonic acid and watery vapour are cast out. Cream, as we 

 have elsewhere stated, consists chiefly of the oleaginous or hydro- 

 carbonaceous elements of the milk, their source being the Ibod ; 

 but if these are consumed while still in port within the blood to 

 keep up the heat of the body, it follows as a consequence that a 

 diminished amount will be found in the milk. Piotection from 

 the cold and inclement weather of v/inter thus becomes indirectly 

 the cause of supply of a given quantity of food, and the same 

 protection is no less beneficial in allaying undue excitation during 

 the heat of summer. 



Ithly, Exertion. — To a considerable extent exertion proves 

 detrimental to the condition of a milking animal, in the same 

 manner as does exposure to a low temperature ; while the two com- 

 bined are sure to be attended with serious consequences. By the 

 increase of respiration which takes place consequent on exertion 

 the hydro-carbonaceous substances are more rapidly consumed, and 

 a diminution of cream is the result. Cows pastured on the out- 

 lying parts of the farm will rarely yield the same amount of 

 butter which they would do if kept near at home, all other things 

 being equal. 



It has been stated on very good authority that cows pastured 

 in mountainous districts, as in Switzerland, where they are obliged 

 to use a great deal of muscular exertion, and are much exposed 

 to atmospherical influences, are excellent as cheese-making 

 animals, but that their milk is deficient of cream. The explana- 

 tion of this is to be found in the physiological fact we have pre- 

 viously spoken of, namely, the consumption of the hydro-car- 

 bonaceous elements of the system. It appears, however, that there 

 is not merely a diminution of these matters but a positive increase 

 in the amount of caseine, which seems to prove that this is derived 

 from the disintegration of the azotised tissues of the body. We 

 might here close our account of the principal causes which modify 

 the secretion of milk, both in quantity and quality, but it is 

 necessary that we briefly allude in the last place to — 



Food. — Of itself there is no one cause so potent for good or 

 evil as the supplying of milking cows with proper or improper 

 food. To obtain all the benefits which we desire, care should be 

 taken that the aliment should be riclj, as has been previously 

 stated, in all the elements of blood. Good blood makes sfood 



