12 STERILITY 



on the fact of the supposed races of nature being 

 sterile, though none of the domestic ones are ? 

 Mr Herbert (and) Koelreuter have shown external 

 differences will not guide one in knowing whether 

 hybrids will be fertile or not, but the chief circum- 

 stance is constitutional differences 1 , such as being 

 adapted to different climate or soil, differences 

 which [must] probably affect the whole body of the 

 organism and not any one part. Now wild animals, 

 taken out of their natural conditions, seldom breed. I 

 do not refer to shows or to Zoological Societies where 

 many animals unite, but (do not ?) breed, and others 

 will never unite, but to wild animals caught and 

 kept quite tame left loose and well fed about houses 

 and living many years. Hybrids produced almost 

 as readily as pure breds. St Hilaire great distinc- 

 tion of tame and domestic, elephants, ferrets 2 . 

 Reproductive organs not subject to disease in 

 Zoological Garden. Dissection and microscope show 

 that hybrid is in exactly same condition as another 

 animal in the intervals of breeding season, or those 

 animals which taken wild and not bred in domesticity, 

 remain without breeding their whole lives. It should 

 be observed that so far from domesticity being un- 

 favourable in itself (it) makes more fertile: [when 

 animal is domesticated and breeds, productive power 

 increased from more food and selection of fertile 

 races]. As far as animals go might be thought (an) 

 effect on their mind and a special case. 



But turning to plants we find same class of facts. 

 I do not refer to seeds not ripening, perhaps the corn- 

 found that they were sterile together. See the case of the red and blue 

 Anagallis given from Gartner in the Origin, Ed. i. p. 247, vi. p. 368. 



1 In the Origin, Ed. i. p. 258, where the author speaks of constitutional 

 differences in this connexion, he specifies that they are confined to the 

 reproductive system. 



2 The sensitiveness of the reproductive system to changed conditions is 

 insisted on in the Origin, Ed. i. p. 8, vi. p. 10. 



The ferret is mentioned, as being prolific in captivity, in Var. under 

 Dom., Ed. 2, ii. p. 90. 



