68 Tin: pour segregative principles. 



According to the New Orleans Times- Democrat* there are on the 

 shores of Louisiana, near the mouth of the Mississippi river, two tvpes 

 of cats. The gnat majority are like the cats of other regions, but a 

 small tribe on Tarpon Island have apparently lost all aversion to being 

 in the water. Their separation from other families of cats has allowed 

 of their establishing their habits of feeding on entirely new lines of 

 tradition, for they all wade freely in the shallow waters of the beach 

 hunting for small fish; and three or four of the bolder ones swim off 

 to oyster boats lying at anchor near by. This is an example of parti- 

 tion allowing an innovation to be established through election as a 

 permanent habitude; and as Captain Bosco, who owns these cats, 

 says it is many years since they began to go into the water, we have 

 r< ason to believe that coincident selection has begun to operate in 

 producing a breed whose innate instincts are better adapted to this 

 mode of life than were those of the original stock from which thev 

 prang; or may it not be possible that the direct inheritance of ac- 

 quired characters has removed the instinctive aversion to water that 

 belongs so universally to cats? If, now, after the habits and innate 

 instincts of the new breed are well established, several pairs of them 

 should be taken to a part of the shore where other cats possessing 

 the nsnal instincts of the species are found, it is possible that their 

 special endowments and social habits might lead them to associate 

 with each other, and thus to perpetuate the habits alreadv formed, 

 and to breed with each other. If such should be the case, it would be 

 an example of social and industrial partition, leading to discriminate 

 isolation and tending to produce permanent segregate breeding. As, 

 however, the segregative social instincts of the cat seem to be weak 

 c< -mpared with those of most mammals, the opportunity for establish- 

 ing separate races of cats is not as good as in the case of most domestic 

 species. 



t-4. Cooperation of Structural Isolation and Structural Selection Illustrated. 



Tht correlation Unit may exist between a given form of isolation and 

 Hit corresponding form of selection is seen in the case of the different 

 forms of impregnational isolation and impregnational selection. Let 

 us consider the case of two varieties of the same species of land snails 

 that arc- prevented from crossing by the fact that in one variety the 

 sexual organs are on the right side of the body (the male organs 

 being near the head and the female organs a little further back), 

 while in the other variety they are arranged in the same way on the 



* New i )rleans Times Democrat, probably January, 1900, as it waseopied by a 

 Philadelphia papei late in January, 1900. 



