PLANT HYBRIDIZATION BEFORE MENDEL 47 



experiment. These, as well as the hybrids in the former case, 

 were found, after most careful experimentation, to be in a slight 

 degree fertile as to the egg-cells, but completely sterile as to the 

 pollen. Kolreuter comments regarding this cross that, in size of 

 the plants and number of flowers, the hybrids far exceed the 

 rustica parent. Whether they exceed the paniculata parent in 

 these respects, he was not prepared to state. 



In case of Nicotiaria paniculata X rustica and its reciprocal, 

 the Fj hybrids resembled each other completely. In the case of 

 the back-cross of rustica upon lustica X paniculata^ all the prog- 

 eny are reported to have approached the type of the maternal 

 parent, i.e., the F^ hybrid ; a few more, others less. The cross, 

 A^. rustica X paniculata^ is reported as furnishing progeny more 

 nearly resembling paniculata than in the original cross. It was 

 found possible to cross A^ rustica X paniculata with A^ perennis, 

 although the cross of percnnis with either rustica or paniculata 

 failed. 



Kolreuter concludes that the continued self-pollination of hy- 

 brids finally results in the re-appearance of the original parental 

 forms. 



His ideas regarding fertilization are interesting. He thought, 

 as has been stated, that a plant was formed by the fusion of two 

 fluid materials of different sorts. 



"since these materials are of different sorts, or in their essence are 

 different from each other, it is easy to comprehend that the strength ot 

 one must be different from the strength of the other. From the union 

 and commingling of these two materials, which occurs in the most inti- 

 mate and orderly manner, according to a definite relationship, there 

 originates another, which is of an intermediate sort, and which conse- 

 quently also possesses an intermediate, compounded force, sprung from 

 those two simple forces. . . . Upon this basis and its operative force, 

 which, according to the different kinds of its twofold fertilizing ma- 

 terial (Saamenstoff), must necessarily be different in the case of every 

 different kind of living machine, rests the gradual, progressive forma- 

 tion of the future plant, its particular organic structure, its specific 

 nature whereby it is distinguished from^ all others, and the proportion 

 of the fertilizing material demanded for a similar new reproduction 

 and, in a word, all those completed conditions (products) which are 

 required for the object to which it is designed." (1, p. 42.) . . . "All 

 the movements and changes, which from the embryo to the time of 

 flowering, take place in every such masterpiece of nature, appear to be 

 directed simply to the great work of reproduction. They all aim at 

 gradually liberating that compound material upon which they are based, 

 and at dividing it again into the two original ground materials; or, 



