Darwin s Artificial and Natural Selection 135 



it is not really necessary to suppose that this would often 

 occur, for the same result could be reached by several stages, 

 even if the discontinuous variations had been small, and had 

 appeared in many individuals simultaneously. After showing 

 that in a number of flowers, especially of the Compositae and 

 Umbelliferae, the individual flowers in the closely crowded 

 heads are sometimes formed on a different type, Darwin con- 

 cludes : " In these several cases, with the exception of that of 

 the well-developed ray-florets, which are of service in making 

 the flowers conspicuous to insects, natural selection cannot, 

 as far as we can judge, have come into play, or only in a 

 quite subordinate manner. All these modifications follow 

 from the relative position and interaction of the parts ; and 

 it can hardly be doubted that if all the flowers and leaves on 

 the same plant had been subjected to the same external and 

 internal condition, as are the flowers and leaves in certain 

 positions, all would have been modified in the same manner." 

 Further on we meet with the following remarkable state- 

 ment : " But when, from the nature of the organism and of 

 the conditions, modifications have been induced which are 

 unimportant for the welfare of the species, they may be, and 

 apparently often have been, transmitted in nearly the same 

 state to numerous, otherwise modified, descendants. It can- 

 not have been of much importance to the greater number of 

 mammals, birds, or reptiles, whether they were clothed with 

 hair, feathers, or scales ; yet hair has been transmitted to 

 almost all mammals, feathers to all birds, and scales to all 

 true reptiles. A structure, whatever it may be, which is 

 common to many allied forms, is ranked by us as of high 

 systematic importance, and consequently is often assumed to 

 be of high vital importance to the species. Thus, as I am 

 inclined to believe, morphological differences, which we con- 

 sider as important, — such as the arrangement of the leaves, 

 the divisions of the flower or of the ovarium, the position of 

 the ovules, etc., — first appeared in many cases as fluctuating 



