PLANT HYBRIDIZATION BEFORE MENDEL 149 



The only general conclusion which Mlmorin was able to derive 

 from the lupine experiment, which he was able to put into the 

 form of what. might be called "rules," are the following: 



1. "a very marked tendency of plants to reproduce the characters of 

 the immediate ascendants ; it is the effect of direct heredity. 



2. "A tendency less strong, but much more persistent, to resemble the 

 mass of the distant ancestors. It is that which has been spoken of under 

 the name of atavism. 



3. "A rapid enfeebling of the tendency to reproduce the characters 

 of an ascendant which is not the immediate author of the plant, if these 

 characters are not those of the mass of the ancestors." (yd, p. 490.) 



Vilmorin summarizes by saying : 



"The experiment already gives indications which, approximated to 

 the results of the experiments made and to be made, will permit, one 

 day without a doubt, to be embraced in a complete and methodical 

 presentation the totality of the laws which regulate the heredity trans- 

 mission of characters in plants." (7b, p. 11.) 



The difficulty with Vilmorin's experiment, as with so many 

 others before that of Mendel, was that it did not undertake to 

 deal with the progeny of plants purposely crossed with the object 

 of determining the numbers and proportions of individuals of the 

 different kinds., that appeared in the second and "variable" gen- 

 eration. So far as Vilmorin's experiment itself was concerned, had 

 the plants been covered, to prevent all pos^^ibility of crossing, 

 and had the numbers of the progeny planted been large, instead 

 of consisting of single representatives of the blue and rose- 

 colored strains, respectively, results of value to students of breed- 

 ing might have been definitely revealed. 



In another memoir (8) Louis de Vilmorin raises the question 

 whether 



". , , the qualities or the characters produced in an individual by ex- 

 ternal and accidental circumstances, such as are peculiar to it and have 

 not affected its ancestrv, are in some proportion transmissible sexually," 

 (p. 2.) 



Instinct, he says, leads him to a negative conclusion, although, 

 as he admitted, determinative data upon the subject were lacking. 

 In undertaking the study of heredity, Vilmorin remarks upon the 

 necessity of disengaging as much as possible the study of heredity 

 from the circumstances which might characterize its action. The 

 latter he finds complicated by the question of the range of the 

 variations in the plant induced by external conditions. 



