132 PLANT HYBRIDIZATION BEFORE MENDEL 



"That, in the hybrids of the first generation, the disjunction takes 

 place at the same time in the anther and in the contents of the 

 ovary; that some of the grains of pollen belong totally to the species 

 of the father, and others to the species of the mother; that in others 

 again the disjunction has not occurred or has just commenced : let 

 us grant again that the ovules are, in the same degree, segregated 

 toward the side of the father and toward the side of the mother. . . . 

 If the tube from a grain of pollen approximated to the species of the 

 male parent encounters an ovule segregated in the same direction, there 

 will be produced a plant entirely reverted to the paternal species. The 

 same combination being accomplished between a grain of pollen and 

 an ovule, both separated in the direction of the female parent of the 

 hybrid, the product will return in the same way to the species of the 

 latter; if, on the contrary, the combination is effected between an ovule, 

 and a grain of pollen, segregated in a direction contrary the one to the 

 other, there will result a true cross-fertilization, like that which has 

 given birth to the hybrid itself, and there will result therefrom a form 

 intermediate between the two specific types." (4c, p. 193.) 



In 1864, Naudin communicated a second report to the Academy, 

 in which he confirmed his previous results as to uniformity in the 

 first generation crosses, the identity of reciprocal crosses, and the 

 "disorderly variation," as he calls it, of the hybrids of the second 

 and succeeding generations. In neither of the two papers is there 

 any numerical classification of the hybrid types. 



Naudin's memoir is often referred to as amounting virtually 

 to a statement of Mendel's law of the disjunction of hybrids. In 

 Naudin's case, however, the statement was of a speculative na- 

 ture, and consisted in the propounding of a scientific hypothesis ; 

 in Mendel's case, his "law" was a scientific conclusion derived 

 as the result of experiment. 



Reviewing this list of statements in the light of present knowl- 

 edge, 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 of heteroz3^gotes, to the parental forms, is a now suffi- 

 ciently well-established fact of segregation according to Men- 

 delian ratios, which, if there be a single pair of allelomorphs in 

 question, takes place on a 1:2:1 basis in each successive self- 

 fertilized generation. The more or less rapid return to its parents 

 of the hybrid fertilized by its parent, means, of course, the split- 

 ting of 50 per cent dominants, or recessives, as the case may be, 

 which are like the parental types in the case in question. 



Naudin propounded, in 1863, a well-reasoned theory of prob- 



