96 Anatomy and Physiology of the Mammary Gland. 



exerts so powerful an influence as to coagulate the caseine of 

 1800 times its weight in milk. It is thus that, in the making 

 of cheese, the curd is separated from the wJiey ; the former con- 

 sisting chiefly of caseine, whilst the latter contains a large pro- 

 portion of the saline and saccharine matter which entered into 

 the original composition of the milk." 



The chemical composition of milk at once shows that its quality 

 will vary considerably with the character of the food on which the 

 animal is fed, being rich in proportion as this conXdJxnsnitroyeiioxis 

 as well as oleaginous and saccharine matters, or substances nearly 

 allied to the latter, such as starch, gum, &c. The animal machine 

 is, howevei*, not to be viewed as a mere chemical laboratory, 

 for vitality plays fully as important a part as chemistry in the 

 elaboration of all secretions. Food, whether fluid or solid, 

 must first be converted into living: blood before ministering: to 

 the wants of the system ; and when we see that milk is so closely 

 allied to the blood, from which it is produced, we cease to feel 

 surprise that a generous and highly nitrogenised diet should give 

 a like condition of the milk. 



We now come to a consideration of 



The causes which influence, beneficially or otherwise, the 

 quality or quantity of milk which is secreted. 



Many cows, as is well known, are celebrated for their milking 

 properties, while others, on the contrary, yield but a scanty 

 supply of the fluid. An investigation of the particular causes 

 in operation to effect this leads us to place among the modifying 

 influences — 



l.sf, Breed. — The Alderney, the Ayrshire, the Holderness, the 

 Kerry, and the Suffolk, are the breeds which, upon the whole, 

 supply us with the greatest number of good milking cows.* Bad 

 milkers may be said to be the exceptions to the rule which 

 obtains with regard to these races. There are, doubtless, many 

 superior milking animals to be met with in our more cultivated 

 breeds of Short-horn, Hereford and Devon, as likewise in others 

 which hitherto have received but little public attention ; but we 

 fear these must be regarded as exceptions rather than otherwise. 



It does not, however, follow as a matter of necessity that a 

 cow which yields a large quantity of milk shall be the best 

 butter-making animal, for it frequently occurs that such milk 

 has an increased proportion of water and caseine, and is therefore 



* The Ayrshire may he considered the true type of a milch cow for the pro- 

 duction of quantiti/, and the Alderney for the production of quality of milk. The 

 Holderness, or more properly speaking, the Yorkshire cow, is a large-framed 

 animal, which, though generally a deep milker, has a great inclination to fatten 

 when not giving milk, and does not, to the same extent as the other two breeds, bear 

 the sole character and appearance of a milk-making-machiue. — H. S. Thompson. 



