Roberts: The Founders of the Art of Breeding 



261 



history of hybrids. He has confirmed 

 that which Sageret already knew, that 

 in a hybrid the characters of the two 

 parents are often shown, not blended 

 but approximated, in such fashion that 

 the fruit of a Datura hybrid, born of 

 two species, the one with a smooth, the 

 other with a spiny capsule, presents 

 smooth places in the midst of a surface 

 generally spiny. This disjunction, as it 

 is called, is explained according to him 

 by the presence in the hybrid of two 

 specific essences, which tend to be 

 separated more or less rapidly the one 

 from the other. He even sees in this 

 disjunction the true cause of the return 

 of fertile hybrids to the types from which 

 they came" (p. 131). (Italics inserted.) 



It is further of great interest to note 

 that the seeds gathered from the smooth 

 side of the capsule reproduced only the 

 smooth-capsule form. Datura laevis, 

 while those taken from the spiny side 

 gave rise only to the spiny form. Datura 

 stramonium. In Verlot's paper, yet 

 to be discussed, further instances of 

 this vegetative segregation, as it may be 

 called, will be found. 



Naudin stated, more clearly and 

 definitely than others had hitherto done, 

 the fact of the general uniformity of the 

 hybrid offspring of the first generation 

 (the Fi generation), as we should say, 

 and the diversity of form, with partial 

 reversion to, or, as we would now put it, 

 the reappearance of, the parental types 

 in the second hybrid (or F2 generation). 

 His language is as follows: "Finally, 

 one may say that the hybrids of the 

 same cross resemble one another in the 

 first generation as much, or almost as 

 much, as the individuals which come 

 from a single legitimate species." 



In contradiction to the results derived 

 by Sageret from his particular set of 

 experiments, Naudin asserts the gener- 

 ally intermediate nature of the first 

 generation hybrids: "All the hybridol- 

 ogists are in accord in recognizing that 

 the hybrids (and it is always the 

 question of the hybrids of the first 

 generation) are mixed forms, inter- 

 mediate between those of the two 

 parent species. This is, in fact, what 

 takes place in the immense majority 



of cases; but it does not follow there- 

 from that these intermediate forms are 

 always at an equal distance from that 

 of the two species." He goes on to 

 remark upon the vagueness with which 

 this relative approximation is deter- 

 mined, resting as it does, largely upon a 

 basis of opinion. He also calls atten- 

 tion to the fact that sometimes the 

 hybrids resemble one of the two parents 

 in certain parts and the other in other 

 parts. Regarding segregation in the 

 second hybrid generation he says: 

 "Very often, to the so perfect uniformity 

 of the first generation, there succeeds an 

 extreme medley of forms, some ap- 

 proaching the specific type of the 

 father, the others that of the mother 

 It is, as a matter of fact, in 

 the second generation that this dissolu- 

 tion of the hybrid forms commences in 

 the great majority of cases. . . . 

 Among several of these hybrids of the 

 second generation, there is a complete 

 return to one or the other of the two 

 parental species, or both, and diverse 

 degrees of approach to these species." 



naudin's explanation 



Naudin now comes to what he 

 regards as the philosophical explana- 

 tion of these facts: "All these facts are 

 naturally explained by the disjunction 

 of the two specific essences, in the pollen 

 and in the ovules of the hybrid. A 

 hybrid plant is an individual in which 

 are found united two different essences, 

 having their respective modes of devel- 

 opment and final direction, which mu- 

 tually counter one another, and which 

 are incessantly in a struggle to disengage 

 themselves from one another." "The 

 hybrid," he says, "in this hypothesis 

 would be a living mosaic, in which the 

 eye would not discern the discordant 

 elements as long as they remained 

 inteimingled ; but, if in consequence of 

 their affinities, the elements of the same- 

 species mutually approximating one 

 another, agglomerate in rather con- 

 siderable masses, there may result, 

 therefrom parts discernible to the eye„ 

 sometimes entire organs, etc." 



Naudin concludes that the pollen 

 and the ovules, and the pollen especially,. 



