Jh 



580 



THE BEGINNINGS OF LIFE. 



determined 



alteration of the 



short space of two months begin to assume the " native " 

 character. M. Costa has recorded a much more 

 remarkable case of the same nature^ namely, that 



' F 



young shells taken from the shores of England and 

 placed in the Mediterranean^ at once altered their 

 manner of growth, and formed prominent diverging 

 rays, like those on the shells of the proper Mediter- 



ranean oyster 



The same individual shell, show- 



■ll 



ing both forms of growth^ was exhibited before a 

 Society in Paris/ Other direct efFects of change in 

 external conditions are perhaps brought about more 



' 



slowly ; thus^ amongst many other examples^ Mr. Darwin 



1 ( 



Animals and Plants under Domestication/ vol. ii. p. 280. 





produced by the influence of altered conditions. And it 

 is often very difficult to make any distinction between 

 the two modes of change, owing to the almost imper- 

 ceptible gradations by which they tend to merge into 



one another. 



What we have "last said may be illustrated 

 quoting a few of the examples cited by Mr. Darwin, in 

 which more or less marked changes in organisms have. ' tkalf^^^"°"^ 



Di 



, Falcofl^'' 



ac 



iDSO 



f India, 

 thec 



on 



ir 



I an intoxicat 

 'is greatly influei 



climate. . . • J-^ 

 of tk apple pn 



< conditions' to which they had been previously ex- 

 posed. Mr. Darwin says ' : — ' With respect to the 

 common oyster, Mr. F. Buckland informs me that he 

 can generally distinguish the shells from different dis- J jjd brightly-co' 

 tricts j young oysters brought from Wales, and laid I ^^ and a d 

 down in beds where "natives" are indigenous, in the T ofAmerican tr( 



)!eo compared 

 Mr.Meehan'. ; 



t 



to differ from 

 mtle leaves be 



and havi 



r 



\ 



% 



\ smaller, ; 



1 



'P 



'°C. .\c:. 



