LAW OF PEOPAGATION. 79 



live proportions of all its parts, but the selection of all good 

 qualities, and avoidance of all bad. The aim is to perfect the 

 organization of domestic animals as far as it can be within the 

 limits prescribed by Nature, for all useful puri3oses. This has 

 been attempted thus far chiefly by observation and experi- 

 ment, without well defined and settled principles. And 

 though much has been written and published on the subject, 

 still persons the most experienced in the art of breeding, and 

 who have obtained the greatest amount of knowledge upon it, 

 feel and confess that there are agencies or principles whose 

 nature and power are dimly discerned or vaguely surmisedf 

 operating beyond the bounds of their experience and knowl- 

 edge. The author of the only distinct treatise in our coun- 

 try on the "Breeding of Domestic Animals," which contains 

 nearly all the cream of previous publications, makes this ad- 

 mission : " It is ti'ue that some of these laws are hidden from 

 us, and much regarding them is but imperfectly understood. 

 What we do not knoiv is a deal more than ivhat we do know." 

 That an able and intelligent writer, after making a thorough 

 investigation of a subject, should admit concerning it, that 

 " what we do not know is a deal more than what we do know," 

 is a singular acknowledgment. Inasmuch as I enter into this 

 unknown and comparatively unexplored field of inquiry, with 

 an attempt to develop some of these hidden laws, I crave 

 your kind indulgence, and respectfully ask for an attentive 

 hearing, and that a free and frank discussion may follow. 



LAW OF PROPAGATION. 



Many years since, while attending professionally families of 

 ditferent nationalities, the inquiry arose. What made such a 

 difference in these families as to the number of children? 

 And then the question took a broader sweep, extending to the 

 changes of population and their causes in the history of dif- 

 ferent races and nations ; and this led to a careful examina- 

 tion of all works treating especially of such topics. As a 

 result of my inquiries, I became convinced that there was a 

 great general law of propagation, based upon physiology, 

 that applied, not only to human increase, but that pre- 

 vailed throughout the whole animal and vegetable kingdoms. 

 In testing this law by the changes that had taken place in 



