Roberts: The Founders of the Art of Breeding 



267 



quantity of them for one to find a dozen 

 which showed, even to a feeble degree, 

 the irregularities of form, so charac- 

 teristic of the first lot. The two sow- 

 ings were so different from one another 

 that, if one had not known their deriva- 

 tion, one would never have been able to 

 believe that they were such near 

 relatives. The great majority here 

 were perfectly normal; as to the small 

 number of those which showed traces 

 of the maternal monstrosity, this mon- 

 strosity was limited to fronds bi-lobed 

 or tri-lobed at the top, with the edges 

 more or less sinuous or a little slashed; 

 yet this alteration most often did not 

 reach more than one or two fronds on 

 the same individual" (p. 98). 



verlot's summary 



Verlot summarizes his views upon 

 hybrids in the following words, which 

 are worth reproducing because they 

 fairly well represent the general knowl- 

 edge of the time, as follows: (1) "Hybrid 

 fecundation is not able to produce 

 anything but variations which will be 

 able, it is true, to multiply themselves 

 mechanically, but which will not be 

 fixable, and which consequently cannot 

 be brought to constitute rates or varie- 

 ties, the products which arise from them 

 being sterile, or if they are fertile, 

 having only a fertility limited to a few 

 generations, or disappearing after a 

 certain time by the disjunction of the 

 types. (2) One of the characters of the 

 hybrids is also a great development of 

 the vegetative organs, coincident with 

 less abundant flowering. They are in 

 general intermediate between the species 

 types, but often approach more the 

 father. (3) The hybrid, self-fertilized, 

 returns more or less rapidly to the 

 parents. (4) The hybrid, fertilized by 

 a parent, returns also promptly to the 

 parent. (5) Crossing — that is to say, 

 reciprocal fertilization of varieties or 

 races of the same species — will serve for 

 obtaining new variations, intermediate 

 between the parents, very fertile, and 

 which can be fixed more or less rapidly, 

 and constitute new varieties or races." 



Reviewing this list of statements in 

 the light of present knowledge, we can 



see that they constitute a more or less 

 correct, non-scientific formulation of 

 the truth. For example, the more or 

 less rapid return of hybrids — that is to 

 say, heterozygotes — to the parental 

 forms, is well established today as a 

 fact of segregation according to Men- 

 dclian ratios, which, if there is a single 

 pair of allelomorphs in question, goes 

 on, on a 1.2.1 basis in each successive 

 generation. The more or less rapid 

 return to its parents of the hybrid fer- 

 tilized by a parent is simply the splitting 

 off of 50 per cent dominants or reces- 

 sives as the case may be, and which 

 are the parental types in the case of 

 simple ratios. 



wichura's work 



In 1865 there appeared Wichura's 

 memoir on the hybridization of plants 

 (10), based upon experiments in the 

 crossing of willows, which had occupied 

 him from 1852 to 1858 inclusive. A 

 brief preliminary report had appeared 

 in Flora in 1854, and also within the 

 same year in the report of the Schlesische 

 Gesellschaft. 



Taken as a whole, Wichura's work 

 dealt, not with the investigations of 

 individual specific characters but with 

 species taken entire and crossed as 

 such. As was the general custom, he 

 regarded a "species" as an integral 

 whole that could be crossed in its 

 entirety. With this conception he made 

 what he called "binary," "ternary" 

 and "quaternary" crosses, /. e., crosses: 

 (1) between two species; (2) between a 

 species and a hybrid; and (3) crosses 

 between two hybrids. Besides the 

 smaller list of Wichura's successful 

 crosses, he published a much longer one 

 of his failures, which stand as evidence 

 both of the considerable amount of 

 crossing work that was done and of the 

 scientific integrity of the experimenter. 

 Of the ordinary, or, as he calls them, 

 "binary" crosses, Wichura made, in all, 

 thirty-five successful crosses and com- 

 binations of crosses (of which ten were 

 "binary," /. e., simply crosses in the 

 ordinary sense) between twenty-one 

 different species of willows. 



Although, as has been stated, 



