130 Evolution nf Vegetal Life. 



the crops or between the toes of birds ; floated across waters 

 in old tree-trunks and timbers, or shipped unwittingly in 

 the meshes of sacks or cracks of packing-boxes. I should 

 like to tell how our most troublesome weeds, like the white- 

 weed, or so-called daisy, wnich trades upon the reputation 

 of the " wee, modest, crimson-tippit flower," and a host of 

 others, are pauper-immigrants, some of them anarchists, 

 indeed, naturalized and voters the first year, every one. 

 Against them, high license, local option, and prohibition 

 have been alike unavailing : the American System of Pro- 

 tection has been an utter failure. I should like also to show 

 you the minute degrees by which great changes are usually 

 effected, but perhaps this has been sufficiently done in what 

 I have said in relation to Artificial Selection. Natural Se- 

 lection is simply the happening, under ordinary conditions, 

 of that which man effects under extraordinary conditions. 

 It is simply that which must result, in the nature of things, 

 from the fact that a small fraction only of the whole can 

 survive ; and from the two diverse tendencies in the laws 

 of descent, for like to produce like, and for the child to dif- 

 fer slightly from the parent. Of course the enormous ex- 

 tent of the changes presupposes an enormous lapse of time 

 in which they were effected. But that lapse of time geol- 

 ogy shows to have occurred. 



I will only mention one part of the evidence of adaptation 

 which has been recorded. The conviction was forced upon 

 Darwin's mind, by the results of an immense amount of re- 

 search, that persistent inbreeding is probably detrimental 

 to any plant : that strength results from the crossing of in- 

 dividuals, if not of varieties or species ; and that, with a 

 higher grade in life, comes an increasing tendency to spe- 

 cialization in the reproductive organs, and the interposition 

 of bars to self-fertilization. His most exhaustive study was 

 made among orchids, of which there are some 6000 species. 

 Many of these are epiphytes, or air-plants, and are marked 

 by the strangeness or magnificence of their blossoms. They 

 are also marked by a wonderful tendency to hybridize, which 

 enables florists from month to month to exhibit new forms 

 and colors, sometimes of wondrous beauty, and therefore, I 

 imagine, not closely resembling the dog for which the boy 

 wanted an extra price, because he comprised sixteen differ- 

 ent kinds. 



Darwin found that in nearly all orchids it is impossible 



