444 CONCLUDING EEMAEKS. 



13. That self-fertilization, or in-and-in breeding is 

 not, perse, injurious; 



14. That it is the loss or reduction, in the individuals, 

 of some of the characters, proper to their species, which 

 causes the evil results which are so frequently seen to 

 follow self-fertilization and in-and-in breeding: 



15. That, when the individuals are fully and propor- 

 tionately developed in all the positive characters of 

 their species — that is, when the perfect type, which is 

 normally immutable, is realized in the individuals — 

 they may be self-fertilized, or closely interbred in the 

 nearest degree of relationship, without any evil re- 

 sults. 



Proof of these propositions is found 



First : In the fact that animals and plants in the 

 state of nature, and when first placed under domesti- 

 cation, are susceptible of the evils resulting from 

 close-interbreeding, to a degree corresponding with 

 the amount of reduction or suppression of characters, 

 which either is known to have occurred, or which is 

 implied by the individuals' subsequent development of 

 positive features : 



Second : In the fact that these evil results from 

 close-interbreeding abate (other things equal) in pro- 

 portion as the variations appear under domestication ; 

 or in other words, in proportion as the reduced or 

 suppressed characters which occasioned the evil, re- 

 develop. 



Third : In the fact that, where other things are not 

 equal, viz., — where Man's selection has been so erratic 

 as to preclude the proportionate re-development, in each 



