CONCLUDING REMARKS. 451 



before detailed, the good resulting from Crossing is 

 infinitely varied ; and the close correspondence which 

 is seen to subsist between such variations in the quan- 

 tity of the effects, and the like variations which- are 

 __ pointed out as prevailing also in the quantity of the. 

 cause assigned, proves the theory of Reversion to de- 

 monstration. 



20. Darwin says that it is " a great law of nature 

 that good should follow Crossing." 



An analysis of the facts upon which' he professes to 

 found this law, discloses 



21. That Crossing is not, perse, beneficial; but is the 

 mere occasion of the good which results ; 



22. That the cause of the good resulting from Cross- 

 ing, is to be found in the fact that, in that process, each 

 of the crossed parents contributes, to the formation of 

 the offspring, a character or characters which the other 

 parent lacks ; the physiological good which is observed 

 to follow, being consequent upon that induced, struct- 

 ural remove toward the perfect type, which is thus 

 effected by the union in the offspring, of the positive 

 peculiarities of both parents. 



Proof of these propositions is found 



First : In the fact that the good resulting from Cross- 

 ing is ever observed to be in proportion to the amount of 

 the positive, structural differences of the crossed parents ; 



Second: In the fact that where either parent has no 

 positive features to contribute to the offspring, which 

 the other parent lacks, there is, relatively to such last 

 mentioned parent, no increase of good whatever dis- 

 played by the offspring. 



