PLANT HYBRIDIZATION BEFORE MENDEL 21 



of the male to have borne seeds afterwards, as authors have reported to 

 us, was not effected except by the aid of pollen brought by the wind from 

 somewhere. For no experiment is easier than this ; none can be more 

 decisive for demonstrating the generation of plants." {ib., p. 116.) 



Datisca cannabina, which had grown for ten years in Linnaeus' 

 botanical garden and had been propagated by perennial roots, 

 produced many flowers, but all females, and hence abortive. 



(p. 48.) 



New seeds were obtained from Paris, and a few tested. These 



again gave only females, producing flowers without fruits. Fi- 

 nally, in 1757, seeds were again obtained, from which some of the 

 plants came males, flowering in 1758. These were transported to 

 a place as remote as possible from the female plants. When the 

 male flowers were at the point of discharging their pollen, the 

 inflorescence was shaken over a sheet of paper "until the sheet 

 was nearly covered with the yellow pollen." This was placed in- 

 verted over the blossoming female flowers. A nocturnal frost 

 in this year injured the Datiscas along with other plants; but 

 investigation of the plant, on the flowers of which the pollen had 

 been scattered, showed the rudiments of seeds, whereas in the 

 others not pollinated theie appeared no vestiges of seeds, {ib., 

 p. 119.) 



Jatro'hka urens is reoorted upon as follows: This plant is dioe- 

 cious. The two sexes flowered annually in the hothouse, but the 

 females preceded the males, dropping their petals or their flow- 

 ers, eight days before the appearance of the male flowers. Thus, 

 up to the year 1752, no fruit of Jatropha was obtained. In this 

 year the male flowers were in a flourishing condition on a taller 

 tree, when another small Jatropha set in a pot in the garden began 

 to produce female flowers. This female plant was then set under 

 the staminate tree. This pistillate tree consequently bore seeds 

 which, on being sowed, germinated. On another occasion, pollen 

 of Jatropha which had been kept for four to six weeks was used 

 for pollinating three pistillate flowers which had expanded in 

 the meantime. "These three females turned out to be fruit- 

 bearing, but all the rest in the same corymb became abortive." 

 {lb., p. 120.) 



This practically concludes the record of Linnaeus' own direct 

 experimental contribution to the matter of sex in plants. 



The pollination of the Gleditsch palm in Berlin with the pollen 



