HEREDITY AND VARIABILITY IN PLANTS. 213 



The " Comptes Eendus " of September 27 and October 

 4, 1875, contain an abstract of a paper communicated by M. 

 Naudin to the French Academie des Sciences, of which the 

 text was suggested by a hybrid between the wild Lactuca 

 virosa and a variety of L. sativa, the common Lettuce. The 

 hybrid was an accidental one : its seeds were fully fertile ; 

 a great number of young plants were raised from them, of 

 which twenty were preserved for full development and study. 

 Like other hybrids the original showed no character which 

 was not evidently derived from the two parents ; and, fer- 

 tilized by its own pollen, the offspring all agreed in this 

 respect, although they varied exceedingly among themselves 

 in the division of the parental heritage, no two being quite 

 alike. This exceeding vacillation between the two parental 

 forms, but not overpassing the limits on either hand, — which 

 Xaudin finds to be the common characteristic of fertile 

 hybrids, close-bred, — he names disordered variation (variation 

 desordonnee). His explanation is that the hybrid is a piece 

 of living mosaic, that two specific natures are at strife in it ; 

 in the progeny each endeavors to reclaim its own, like seeks 

 like ; whence in the course of a very few generations (as he 

 first showed in Datura) a segregation takes place, part of the 

 progeny reverting completely to one ancestral type, part to the 

 other. "What Xaudin now insists upon is that out of all this 

 disturbance comes nothing new ; that there is here no varia- 

 tion beyond the line of inheritance ; and therefore from cross- 

 ing no possible development of species. 



To this proposition we accede, so far as respects the direct 

 consecpience of crossing. To fill up the interval more or less 

 between two forms or species with intermediate patterns may 

 tend to the fusion or confusion of the two, but not to the oris-- 

 ination of new forms or species. Although Naudin's own 

 experiments lead him to deny all tendency to variation over- 

 passing these limits, we do not forget that his countryman, 

 the late M. Vilmorin, — working in a different way and with 

 another object, — arrived at a different conclusion. He suc- 

 ceeded, as we understand, in originating floricultural novelties 

 from species which refused to vary per se, by making a cross, 



