26o NATURAL SCIENCE. Oct.. 



depended upon " to come true." Thus, an eminent agriculturist 

 once said to me (a trifle hyperbolically, of course) speaking of the 

 varieties of wheat : " You can almost get a different variety from 

 every grain in a single ear." 



Sir J. D. Hooker records no wild variety of the cabbage [Brassica 

 olcracea, L.). Theophrastus (300 B.C.) only knew three cultivated forms. 

 Pliny speaks of six, but who will count them now ? It would seem 

 as if plants underwent two courses of variation. First, in adaptation 

 to it, by responding at once to a new environment, i.e., definite 

 variation. Then, when this has been thoroughly established, as with 

 all of our ordinary vegetables, they may vary indefinitely, but 

 why they do so no one can tell. Still, taking a broad view of the 

 whole process, it is obvious that all such variations were primarily 

 due to the environment of cultivation ; because they never occur in the 

 wild state. 



Hence, to test the reality of specific characters of wild plants, as 

 Mr. Wallace describes, by their degree of stability under cultivation 

 in a garden, cannot possibly give but the most untrustworthy results. 

 Some may resist for a time the influences of the new artificial environ- 

 ment, others may succumb to them ; but it will be the very best means of 

 forcing them to change; for, as Darwin and Weismann assert, cultivation 

 induces variability. Suppose this test had been supplied to the wild 

 and tall Cineraria cruenta with its small flowers ; what would a 

 systematist now say if he had never known the origin of the modern 

 dwarf kind with large flowers of innumerable colours ? He would 

 undoubtedly call it a new species. 



The rule may be laid down that a species may he constant as long 

 as its environment is constant, but no longer. I have changed the spiny 

 Ononis spinosa, L., the Rest-harrow, both by cuttings and by seed, 

 into a spineless form undistinguishable from the species 0. repens, L., 

 in two years ; but it would have, I doubt not, at once reverted to 

 0. spinosa if I had replanted it in the poor soil from which I took it. 

 It seems, therefore, to be a very hazardous and fallacious method 

 of testing the value of specific or other characters by cultivation. A 

 wild plant may or not change at once. Thus the carrot, Daucus 

 Carota, L., proved refractory with Buckman, but not with Vilmorin, 

 who converted this annual to a hereditary biennial, by sowing the seed 

 late in the season, till the character of flowering in the second 

 season became fixed. 



Indeed, the proposed test is not unlike trying a man's guilt by 

 making him eat an ordeal bean ! 



Mr. Wallace illustrates his remarks by the case of species of 

 Arabis, but quite fails to perceive that it goes to prove my contention 

 altogether. He says: "^. anachoretica has tissue-papery leaves — 

 due to its groii'th in hollows of ihc rock " (my itals.). " Seeds of this plant, 

 when cultivated at Kew, produced the common species A. alpina. 

 The same thing occurs with many plants, as every cultivator knows." 



