PLANT HYBRIDIZATION BEFORE MENDEL 77 



pose of verifying the theory of the sexuality of plants, and car- 

 -ried out with scientific thoroughness and accuracy. 



This outlines the history of the more important experiments 

 known to have been performed in connection with the investiga- 

 tion of sex in plants, to the days of Kolreuter. 



By the middle of the eighteenth century, therefore, little doubt 

 should have remained in scientific minds regarding the existence 

 of sex in plants, or as to the necessity of the pollen as a fertiliz- 

 ing agent. As Kolreuter himself says : 



"The pollen is a collection of organic particles, which in every plant 

 have a definite form ; it is the true instrument in which the male fer- 

 tilizing material (Saamen) is produced, disengaged, and made suited for 

 dissemination." ("Vorlaufige Nachricht," p. 7.) 



Actual experiments in fertilization, many of them between 

 plants of different species, had been successfully carried out in 

 more than twenty important groups of plants, from many differ- 

 ent families. We have also in Kolreuter's work a careful study 

 of the characteristics of hybrids, obtained in sixty-five different 

 hybridization experiments, conducted with species from a dozen 

 different genera, belonging to diverse families, together with an 

 accurate comparison of the characters of the hybrid plants of 

 the first generation with those of their parents. 



A scientific foundation had therefore been laid for genetic work 

 in the breeding of plants. The value of Kolreuter's own experi- 

 mental work was doubted, however, by influential contemporary 

 critics, although Sageret (10), whose opinion should have carried 

 weight, said of it : 



"Having several times repeated his experiments, I have occasion to con- 

 vince myself more and more of his exactitude and of his veracity; I be- 

 lieve then that he merits all confidence." 



Kolreuter began with perfectly settled convictions regarding 

 sexuality in the plant kingdom. In the preface to his "Vorlaufige 

 Nachricht" of September 1, 1761, he states that he would have 

 accompanied his manuscript material with special proof concern- 

 ing sex in plants, if he had not considered it in his present view 

 (bey gegenwartiger Absicht) as in the highest degree superfluous. 



"The most important of these [e.g., the proofs in question] anyone can 

 deduce therefrcm, who has only to a tolerable degree a conception of 

 this subiect. I flatter myself in the meanwhile with the good hope that, 

 if not through the already propounded propositions alone, yet at least 



