THE ELEMENTS OF ORGANIC EVOLUTION. 



97 



are for the most part those of minor importance, the 

 superficial traits of the species rather than the deep- 

 seated qualities of the group. But these are none the 

 less real, and to this series of influences much of the 

 variety of the life of the globe must be attributed. 



The survival of the existing, which is the basis of 

 most of the distinctions between one species and another, 



is not less real than the survival of the 

 Survival of the f^^^Q^^. j^ making up the fauna or flora 

 existing. ... ,, 



of any region, those creatures actually 



present must leave their qualities as an inheritance. If 

 they can not maintain themselves, their type passes 

 away as unfit. If they maintain themselves in isolation, 

 their characters become persistent as those of the new 

 species. 



Still other factors in organic evolution may be more 

 or less clearly defined, either in connection with those 

 above mentioned or as fundamentally distinct. 



One of these is the following: The transmission of 

 characters of the parent as distinct from proper hered- 

 ity. A starved hill of corn means ill- 

 Nutrition in • u J • T^u 1 .. J J 

 . . nourished grains. The plants produced 

 transmission. '^ 



from ill-nourished seeds may be stunted 



by lack of vitality or lack of starch without any change 

 or deficiency in the germ itself. In like manner feeble 

 children may owe their traits to the temporary illnesses 

 of a strong mother. A sound mind demands a sound 

 body, and a sound body is necessary to well-nourished 

 offspring. With the characters of the germ cell these 

 conditions have nothing to do, and their homologue is 

 found in such defects as insufficiency of milk. 



VIII. Inheritance of Acquired Characters. — The in- 

 heritance of acquired characters mentioned above, a 

 process of transmission possibly different from germ 

 heredity, has been lately the subject of much discussion. 



