NEOLAMARCKISM 



401 



Ocean. As respects climatic variation in birds, Pro- 

 fessor Baird first took up the inquiry, which was 

 greatly extended, with especial relation to the for- 

 mation of local varieties, by Dr. J. A. Allen,* who 

 was the first to ascertain by careful measurements, 

 and by a study of the difference in plumage and 

 pelage of individuals inhabiting distant portions of 

 a common habitat, the variations due to climatic and 

 local causes. 



" That varieties," he says, " may and do arise by 

 the action of climatic influences, and pass on to 

 become species; and that species become, in like 

 manner, differentiated into genera, is abundantly 

 indicated by the facts of geographical distribution, 

 and the obvious relation of local forms to the con- 

 ditions of environment. The present more or less 

 unstable condition of the circumstances surrounding 

 organic beings, together with the known mutations 

 of climate bur planet has undergone in past geologi- 

 cal ages, point clearly to the agency of physical 

 conditions as one of the chief factors in the evolu- 

 tion of new forms of life. So long as the environing 

 conditions remain stable, just so long will perma- 

 nency of character be maintained ; but let changes 

 occur, however gradual or minute, and differentia- 

 tions begin." He inclines to regard the modifica- 

 tions as due rather to the direct action of the con- 

 ditions of environment than to " the round-about 

 process of natural selection." He also admits that 



* " The Influence of Physical Conditions in the Genesis of Spe- 

 cies," Radical Review, i., May, 1877. See also J. A. Allen in Bull. 

 Mus. Comp. Zoal., ii., 1871 ; also R. Ridgway, American Journal of 

 Science, December, 1872, January, 1873. 

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