PLANT HYBRIDIZATION BEFORE MENDEL 133 



able truth; Mendel, however, in 18^, formulated a statement of 

 ascertained fact. 



In 1865, Naudin, who had won so much credit for his memoir 

 on hybridization in 1863, published a paper on what he termed 

 "disordered variation" in hybrid plants, occurring as the result 

 of crosses he had made between a variety of cultivated lettuce 

 and a wild species [Lactuca virosa). Of the cross he says: 



"The hybrid of the first generation was very fertile, and from the 

 seeds sprang a multitude of young plants, very varied in aspect, which 

 intermingled in all degrees the characters of the two species." 



Of these Fo plants, twenty were preserved, concerning which he 

 remarks that they presented as a whole "all the phenomena of 

 the most disordered variation." 



No two individuals of the twenty in the second generation were 

 alike, and yet, so far as the characters were concerned, nothing 

 new was seen to appear that had not already existed in the one 

 or the other parent. 



"One essential point to bring forward here," Naudin adds, "is that, 

 in this overlapping of the characters of the two different species, one 

 does not see anything new appear, anything which does not appertain 

 to the one or to the other. Variation, as disorderly as it may be, moves 

 between limits which it does not transgress. The two specific natures 

 are engaged in a struggle in the hybrid, to which each one brings its 

 contingent ; but from this conflict there do not really issue new forms ; 

 that which is produced is never but an amalgamation of forms al- 

 ready existing in the parent types. The hybrid is but a composition of 

 borrowed pieces, a sort of living mosaic, of which each piece, discernible 

 or not, is ascribable to one or the other of the producing species." 



Naudin concludes that not the surrounding medium, but the 

 nature of the ancestry, is the cause of all the variations seen in 

 plants. He calls attention to the fact that seeds of the same sow- 

 ing, although exposed to the sam.e environment, do not vary in 

 the same manner. 



"We see the variation without any rule, by the sowing of their seeds, 

 of plants subjected since time immemorial to our cultivation, such for 

 example as the vine and the greater number of our fruit trees ; it all 

 brings us to think that they owe it to crosses, probably very ancient 

 and possibly anterior to all domestication, between neighboring species." 



Naudin then answers the question, "Whence comes heredity 

 and what is it," as follows : 



"it is always the passage from one equilibrium to the other, and al- 

 ways along the line of least resistance." 



