184 FIBST PRINCIPLES OF AGRICULTURE. 



and season of milking. Of tlie constituents, fat varies 

 more than the others, though each may vary sufficiently 

 to cause serious differences in the composition of the 

 products made from milk. The accompanying analysis 

 fairly represents the average amounts and proportions of 

 the constituents in normal milk: — 



"Water 87.50 per cent. 



Fat 3.50 " 



Casein and Albuminoids 3.75 " 



Milk Sugar 4.50 " 



Ash 0.75 " 



100.00 



This average composition of milk has served as the 

 basis in many States for the enactment of laws to pre- 

 vent watering and other forms of adulteration. It must 

 be remembered, however, that normal or whole milk will 

 show wide variations from this standard in both direc- 

 tions ; that is, it may be very much richer or very much 

 poorer. The solid matter in milk is called " Total Solids." 



The Influence of Breed. — It has already been stated 

 that cattle are divided into two classes : on the one hand, 

 those in which the tendency to secrete milk is largely 

 developed ; and on the other, those in which the tendency 

 to form flesh and fat has been especially encouraged. 

 The result of this careful selection is the formation of a 

 distinct milk type, in which the width and depth of the 

 hind part of the animal and the udder are especially 

 prominent features. 



The dairy breeds are, however, further classified into 

 milk and butter breeds ; that is, those which give a large 

 quantity of average quality, and those which give a 

 smaller quantity of a higher quality. The following 



