254 Cattle Problems. 



small extent of growth, or a dwarfed size, according to 

 the small supply of nutrition it receives. As the embryo 

 cannot make growth without breeding blood, its extent of 

 growth can only be in proportion to its supply of nutri- 

 ment. Digestive power is limited by two conditions : 

 First, by extent of space or size of the stomach and ali- 

 mentary canal to contain the crude substances that supply 

 the crude material of blood. Second, by the quantity of 

 digestive or solvent fluids which, being derived from the 

 blood, cannot exceed their natural proportion to the quan- 

 tity of blood supplying them. The quantity of blood de- 

 rived from a given amount of feed cannot exceed the 

 quantity of blood elements, the use of which depends on 

 the digestive power, which varies according to the mus- 

 cular vigor and extent of exercise and breathing. The 

 total blood supply is according to two sources of natural 

 demand : First, to nourish the system of the cow ; and, 

 second, to develop and maintain the three breeding stages 

 or processes aforesaid. The instances are exceptional and 

 few in which cows produce more blood than is required to 

 nourish their own systems, and also to continue their 

 kind, by providing blood and blood heat, and to supply 

 blood nutrition during the preparatory and embryo breed- 

 ing processes ; and to form milk also to continue the em- 

 bryo growth in that of the calf. And it is certain that 

 embryos can and do in very many cases receive and or- 

 ganize all the breeding blood — all that residue which is 

 not used in nourishing the cow's system; and afterward, 

 as calves, consume all the mother cow's milk.* 



When embryo calves receive all the breeding blood — as 

 when pregnant cows are not milked — they grow much 

 hirgcr, according to their larger supply of nutrition, be- 



* Siinn' Short.-horn bret'tliM-e, iinclerstanding this fact, hiive for generations 

 allowcrl nximbereof their cows to suckle their own calves ; ana, in some 

 cases, two common cows supply one Short-horn calf. 



