190 BOARD OF AGRICULTURE. 



the case, — the result depending upon the structure and com- 

 position of the forces which severally are engaged. In mon- 

 grels we find great variability and little prepotency, as a rule, 

 all resulting from the doctrine of persistence of force. 



The other effects of inbreeding — as the transmission of 

 defects in an accumulated form — fall directly under the fact 

 of inheritance, and need not be considered in this place. 



The unequal fertility between reciprocal crosses connects 

 the consideration of mongrels and hybrids, and seeks explana- 

 tion from the same laws. 



In crossing animals of the same race we have a union of 

 forces under the laws of breeding, but on account of our little 

 knowledge concerning the relative strength and the combined 

 action of the forces we. are using, the results are apt to be 

 very variable. When two forces meet in antagonism, each 

 is modified and changed according to the law of mechanics, 

 but neither force is obliterated ; the effect of the struggle 

 remains, while the forces may be in abeyance. Like the 

 circular ripple of the pebble dropped in the water of smooth 

 surface, the effect is ever acting, ever extending, and we thus 

 have a series of actions modifying changes for all time. 

 Characters in an animal are never obliterated, but may dis- 

 appear from our view. We have, in crossing, a means for 

 the modification of race, by producing changes through direct 

 antagonism of force. We also have in free crossing a means 

 for the preservation of uniformity between members of the 

 same race. Like a two-edged sword, the law of crossing cuts 

 both ways, according as its principles are applied, and under 

 the government constantly of the great law of nature, — that 

 of the persistence of force. As the antagonism of forces may 

 be considered in the light of a mutual absorption, other forces, 

 too weak to otherwise appear in a form recognizable to us, 

 may appear. Hence, we say, that crossing produces a ten- 

 dency to reversion or atavism. 



Selection. — This is simply an expression of a means to an 

 end. It signifies the accumulation of a force in a chosen 

 direction. As used by the breeder, selection means modify- 

 ing the laws of animal nature through human knowledge and 

 skill, so as to predetermine the result. If unconscious, it is 

 the accumulation of prepotency through law, not under the 



