( 245 ) 



RELATIONSHIP OP SPECIES. 

 By H. Panton. 



(Concluded from p. 101.) 



Let us in our argument term Darwin's slowly evoluting 

 "indefinite variation" a "variant," in opposition to his "de- 

 finite " or " spontaneous variation," the mutant of De Vries. 



The latter great exponent of the mutation theory is of opinion 

 (as above stated) that evolution proceeds from a sudden jump ; 

 that a new species is suddenly born ; a mutant. What is the 

 difference between the slow changing variant of Darwin and the 

 suddenly evoluted mutant of De Vries ? Is it only one of degree? 

 If so, there is no difference. I believe that a mutant is defined 

 as a type that gives inheritable powers, but that a variant does 

 not transmit this power, or hand on its variation to its offspring. 

 This distinction is clear, but is it invariable ? 



A mutation, I take it, is the result of a power in the germ 

 plasm to give forth suddenly a new form desired by or agreeable 

 to Nature, whether acting through environment or nutriment. 

 It is a natural evoluting process for the manufacture of new 

 forms, and is recognized by Darwin, and although not considered 

 by him to be as effective in evolution as his more graduating 

 variant, is, it is not unreasonable to suppose, apparently like 

 the latter, acted upon by " external conditions affecting the 

 germ-cells." One is therefore forced to the conclusion that a 

 mutant and a variant arise from the same cause. 



But some say, as above, that a variant does not transmit 

 its characteristics. Without entering into the argument at 

 all fully, it would appear that there are a large number 

 of cases where variation is hereditary. Nearly all domestic 

 animals are moulded into various forms almost entirely by this 

 means. 



And let it not be forgotten that in these domestic forms (or 



