No. 1.] ORGANIC VARIATION. 293 
variable.! Also in domesticated animals, the males are more 
variable (Darwin). Why the wing should be less variable 
than the other dimensions, is difficult of solution on any other 
ground, than that the wing has but one main function, while 
the tarsus and the bill are put to a diversity of uses, which 
would result in the two latter being more variable. 
III. ON THE ORIGIN OF VARIATION. 
The doctrines of Lamarck and Darwin teach that the 
organism is more or less adapted to its environment ; even 
Bateson (/.c., p. 10) grants a certain amount of such adaptation, 
though in the main he militates against the assumption of any 
complete degree of adaptation. We may then start out from 
the assumption, for the correctness of which there is strong 
evidence, that it is a biological law for the organism to be more 
or less completely in correlation with its environment, in order 
to insure its existence. It is even permissible to go further, 
and assert that its chance of existence will stand in direct pro- 
portion to the degree of its adaption to the environment. (By 
the term environment, which is used here in its full sense, is 
meant the sum total of all the external forces acting upon the 
organism.) Therefore it is obvious that the chance of the 
organism’s existence must depend upon its degree of correla- 
tion with the environment, or, in other words, with its readiness 
of response to the external conditions. This law being so 
reasonable, and so thoroughly in accord with our modern 
biological ideas, it is not necessary to enter into any further 
discussion of its plausibility. 
For the purpose of advancing further deductions as to the 
primal cause of variation, we may proceed from the considera- 
tion of a species which, we have reasons to conclude, is, com- 
paratively speaking, perfectly adapted to its environment. We 
1 Tt is not impossible, that in birds, as in man, the female may be more con- 
servative and less progressive than the male, and passing a more (physiologically) 
monotonous existence than the latter, is less influenced by the struggle for 
existence, and accordingly is less variable structurally. This suggestion has, how- 
ever, no more value than that of a mere comparison. 
