PHILOSOPHY OF BREEDING. 145 



And it is here where pigs can be used to great advantage. 

 The solid faeces from pigs do not readily ferment. They con- 

 tain little nitrogen. The nitrogen, which is the active agent 

 in fermentation, is found in the urine. If pigs are fed on 

 rich, nitrogenous food, and the urine is added directly or 

 indirectly to the manure-heap, consisting of horse, cow and 

 sheep droppings, it will greatly improve the whole mass. If 

 properly managed, the heap will steadily ferment all winter 

 and be in good condition for use in the spring, even for man- 

 golds or potatoes. How far we can carry the fermentation to 

 advantage, and under what conditions, is a point yet to be 

 determined. 



Mr. Harris's paper was followed by an essay on 



THE LAW OF INHERITANCE; Or, THE PHILOSOPHY OF 

 BREEDING. 



BY DR. E. LEWIS STURTEVANT, OF FRAMINGHAM. 



It is now nearly three years since I made my first attempt to 

 write a work on the breeding of domestic animals. I had 

 collected a considerable mass of information, chiefly so-called 

 facts, and it seemed an easy matter to bring these into shape 

 for the illustration of principles which could be enunciated as 

 laws. I soon, however, realized the difficulty of using this 

 material to produce an harmonious result, as the grouping was 

 not only arbitrary, but the laws which they were intended to 

 illustrate were but empirical formulas, whose mutual connec- 

 tions could not be shown. I therefore determined to seek, 

 through further study, a solution for my difficulties ; and I 

 may here say that my realization of the importance of force 

 as fashioning the phenomena of vitality came entirely from a 

 series of inductions. The facts were grouped under laws 

 which seemed to formulate the conditions under which they 

 occurred, and these laws, in turn considered as unities, pointed 

 unmistakably to a superior law, which in its turn influenced 

 their occurrence, — the law of persistence of force. This 

 brief paper is not presented in order to prove a theory, 

 but as an outgrowth arising from the supposed recognition 

 of a cause. 



19 



