Roberts: The Founders of the Art of Breeding 



263 



shall derive from this fact the conse- 

 quence that the faculty of varying, 

 which is proper to the plant, augments 

 with culture. If we observe, then, that 

 the plants cultivated in our gardens 

 which have varied the most — as, for 

 example, the dahlias, the roses, the 

 camellias, the rhododendrons, the po- 

 tato, etc. — are not borrowed for the 

 most part from our flora, nor from one 

 of the neighboring floras, but on the 

 contrary come from distant countries, 

 where they grow under conditions often 

 absolutely different from those in which 

 we cultivate them, we shall conclude 

 that the more a species is depatriated 

 the more it will easily vary" (p. 30); 

 and again: "The more plants are cul- 

 tivated, the greater their variations are, 

 and, by the same token, the easier they 

 are to fix. We will possibly be contra- 

 dicted, but we do not hesitate to con- 

 sider, once more, long-practiced culture 

 as one of the most favorable antecedents 

 to the rapid fixation of variations" 

 (p. 38). 



We now know at least that the in- 

 creased variation manifested by wild 

 plants, when brought into cultivation, 

 is probably due to the removal of the 

 restricti\'e influences of -competition 

 rather than to any actual increase in 

 the range of heritable variability itself. 



Verlot cites, as examples of the 

 changes supposedly wrought by cul- 

 ture, the changes brought about in the 

 roots of such plants as beet and parsnip, 

 in the production of dwarf plants, in 

 various modifications in general habit, 

 such as fastigiate, pyramidal and weep- 

 ing variations in trees ; in the appearance 

 of variations with laciniate or other- 

 wise modified leaves; in varieties with 

 leaves colored white, yellow, red or 

 brown ; in the arrangement of the leaves, 

 as in the sudden appearance on an 

 ordinary alternate-leaved plant of Rosa 

 alba, of a shoot with opposite leaves, 

 propagated as Rosa cannahifolia. From 

 the evidence he concludes that cultiva- 

 tion sets up within the plant a condition 

 of instability, which gives rise not only 

 to seed variation but to variation within 

 the plant itself — what we would call 

 bud- variation or somatic segregation — 



as in the case just cited, the case of a 

 chrysanthemum reported which bore at 

 the same time yellow and rose-colored 

 flowers, and of a citrus fruit half-and- 

 half orange and lemon. Another case 

 cited by Verlot is that of a variegated 

 Camellia imperialis which, for twelve 

 years, had constantly given brilliant 

 white flowers set off with rose-colored 

 striations and variegations, and upon 

 which a small branch appeared one year 

 bearing three flowers, in a group of a 

 uniform rose color, the same in tint as 

 that of the striations and variegations 

 of the other flowers. 



"It is evident, in these cases," says 

 Verlot, "that the colorations disjoin 

 and that this variation returns by dis- 

 junction to its colored types, as we have 

 indicated for certain plants of hybrid 

 origin, (p. 67). As we see," he says, 

 "by the sole fact that a plant is cul- 

 tivated, it is forced to vary. The 

 instability of a cultivated plant is even 

 evident in certain cases in such a way 

 that it does not only manifest itself in 

 the direct descendants of the plant, but 

 also in the plant itself. Thus, while the 

 generality of the branches of a plant 

 bear leaves, flowers and fruits of definite 

 forms or colors, a branch is sometimes 

 produced in which the leaves, flowers, 

 and fruits present completely different 

 characters. We recognize that culture 

 has been and is still the essential cause 

 of the variation of plants, and that 

 thereby man has, so to speak, com- 

 pelled them to re-clothe themselves 

 with new forms appropriate to his needs 

 or to his caprices" (p. 5). 



The above statement excellently pre- 

 sents the older point of view regarding 

 variation. Such cases as the rose, 

 chrysanthemum and orange, and the 

 famous hybrid Cytisus Adami (purpu- 

 reus X laburnum), Verlot accounts for 

 under the guise of Naudin's conception 

 of "disjunction": "It is by disjunction 

 that, in these last cases, the speciflc 

 forms thus reappear in hybrid plants, 

 and it is with woody plants, it will be 

 noticed, that this fact presents itself; 

 individuals, that is to say, which, per- 

 sisting for long years, must achieve all 

 the phases of existence of a hybrid plant. 



