MANUAL OF AGPJCULTURE. 281 



changes appear very simple, and yet, how difficult is it to con- 

 ceive by what mysterious influence the mere contact of this 

 decaying membrane, or of the casein of the milk, can cause the 

 elements of tlie sugar to break up their old connection, and tf> 

 arrange themselves anew in another prescribed order, so as to 

 form a compound endowed with properties so very different as 

 those of lactic acid." 



Lactic acid is also produced during the churning of cream, and 

 is supposed to aid the violent mechanical agitation, in breaking 

 the walls of the oily cells or globules, after which the butter 

 separates in mass from the sour butter milk. In the ordinary 

 domestic manufacture of cheese, " rennet," an acid decoction 

 prepared from the dried stomach of a calf, is what is ordinarily 

 added to the milk, for the purpose of coagulating or curdling the 

 casein. 



As cow milk is such an invaluable article of the human 

 dietary, calves are often early deprived of this, their natural food, 

 or, at all events, only partake of it after its cream has been ab- 

 stracted. But suitable artificial food is substituted, rich in the 

 various proximate constituents. But even in those cases where 

 a fair amount of milk is afforded to them, it is sometimes usual 

 to mix with it linseed, or some similar meal, whenever the calf 

 can eat artificial stuffs, and nutritious green food is provided as 

 well. Lambs and young pigs are not prematurely deprived of 

 mother's milk ; but she is fed with food calculated to enrich the 

 <|ualities of her milk. 



Before the introduction of turnips, owing to the want of green 

 or juicy food for the live stock during winter, the animals had 

 attained, as a rule, their full growth nnd maturity, ere they were 

 fattened enouc(h for slaughtering-. Throucrhout summer and the 

 milder months they had the range of the pasturage ; and in 

 winter they were turned into the fold-yards, more indeed for the 

 purpose of trampling down and converting the litter into manure, 

 than of iK'ing carefully tended, and provided with nourishing- 

 food, their dietary being almost entirely composed of hay and 

 straw. Sheep also had to subsist entirely upon the natural 

 j)asturage ; few, if any, were kept on the arable farms. The 

 state of matters is now entirely different. A variety of green 

 crops is cultivated ; there is the choice of an immense assort- 

 ment of artificial feeding stuffs, and every breed (if stock has 

 been improved to the develoi»ment of the most extraordinary 

 quiilities of speedy and economical fattening. Conse(piently, 

 stock is kept in every district in amazingly increased numbers, 

 and sent to the meat market in ])rinie condition, at a compara- 

 tively early age. Even in sikIi counties, where, from i)hysical 

 and climatic obstacles, a large projiortion (tf the land neces- 

 sarily remains in its natural condition, the cultivation of the 

 residue is whollv directed towards stock-breeding and rearing, 



