CROSSING AND CLOSE-INTERBREEDING. 213 



esteemed so mutually incompatible, — of those who 

 concur in, and of those who demur to Darwin's 

 conception, are shown to be in perfect harmony with 

 each other. All the discord is harmony, when under- 

 stood. The variations in the quantity of the results of 

 crossing and of close-interbreeding, are a mighty maze, 

 but not without a plan. Each degree of effect, answers, 

 faithfully, to a corresponding degree of the cause as- 

 signed ; and, where the cause is observed to be absent, 

 there the effects are seen not to prevail. 



The theory of reversion, — or theory of the necessity 

 of the proportionate development of all the characters 

 of a species, — explains, in the simplest manner possi- 

 ble, all and each of the many different variations in 

 the quantity of the effects of crossing, and close-in- 

 terbreeding; and explains the irregular recurrence of 

 such effects. By it, scientists, and every breeder, fan- 

 cier, horticulturist, and agriculturist, are enabled to 

 solve the question, why there exists such a grada- 

 tion, even within the same species, between those in- 

 dividuals evincing the greatest evil effects, and those 

 displaying the least, or none at all; by having dis- 

 closed to them, in the cause, a corresponding grada- 

 tion, between those individuals, lacking a large number 

 of characters, or having them disproportionately de- 

 veloped to the greatest degree, and those individuals 

 possessing all, or nearly all of the characters of their 

 species, fully and proportionately developed. 



It is in the similar departure, of each of the parents 



interbred, from the true mould, or original type of their 



species, that we find the cause of all the disorder 

 19 



