262 



The Journal of Heredity 



"are the parts of the plant where the 

 specific disjunction takes place with the 

 most energy." He goes on to suppose, 

 and here, perhaps he comes closest to a 

 statement of Mendel's view, "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 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 direc- 

 tion, there will be produced a plant 

 entirely reverted to the paternal species. 

 The same combination being accom- 

 plished between a grain of pollen and 

 an ovule, both segregated in the direc- 

 tion 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." 



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 

 generation. In neither of the two 

 papers is there any numerical classifica- 

 tion 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 proposition of 

 a scientific hypothesis; in Mendel's 

 case, his "law" was a scientific conclu- 

 sion derived as the result of experiment. 



Naudin propounded, in 1863, a well- 

 reasoned theory of probable truth; 

 Mendel, in 1868, formulated a state- 

 ment of ascertained fact. 



THE WORK OF VERLOT 



In 1865 B. Verlot, of the Jardin des 

 Plantes at Paris, published a brief 

 memoir which in 1862 had received a 

 prize from the Imperial and Central 

 Horticultural Society, the thesis of which 

 was as follows: "To demonstrate the 

 circumstances which determine the pro- 

 duction and fixation of varieties in orna- 

 mental plants." The memoir is of 

 interest as thoroughly and typically 

 embodying the general point of view of 

 the day concerning hybridization and 

 the origin of new varieties, while afford- 

 ing at the same time much matter of 

 interest from the standpoint of practical 

 horticulture. Verlot presented the view 

 that, while the causes of variation are 

 unknown, they arise under definable 

 circumstances, chief among which he 

 enumerates prolonged cultivation, re- 

 moval from one set of climatic and soil 

 conditions to another, and hybridization. 



The thought of the time did not 

 clearly distinguish a difference between 

 the nature of the changes brought about 

 by the external environment and those 

 arising from sexual fertilization. Both 

 were generally assumed to be equally 

 heritable. Cultivation long continued 

 was considered to have been especially 

 potent in bringing about variation. In 

 Verlot's words: "It is especially with 

 plants cultivated for a great number of 

 years, with those the introduction of 

 which is so ancient that it is lost in the 

 night of time, that one finds profound 

 and multiplied modifications" (p. 4). 



He further voices the then prevailing 

 view regarding the relation between 

 culture and variation: "If we com- 

 pare," he says, "a species in its spon- 

 taneous condition with the same species 

 cultivated, transported, that is to say, 

 most often into conditions of climate, 

 soil, etc., completely different from those 

 where it lived before, we shall be struck 

 by seeing that in our gardens this latter 

 will show deviations of type more 

 numerous than in the wild state. We 



