PLANT HYBRIDIZATION BEFORE MENDEL 49 



ence to be found between it and those of the reciprocal experiment." 

 (p. 120.) 



Pursuing his conception that the activity of the pollen pro- 

 duced a quantitative effect depending upon the amount and char- 

 acter of the pollen employed in fertilization, Kolreuter instituted 

 a series of experiments with Nicotiana species. He found that N. 

 perennis^ pollinated with a small quantity of its own pollen, and 

 a much larger amount of glutinosa produced plants wholly per- 

 ennis, which had no character from glutinosa. Similarly A'', rus- 

 tica^ pollinated in part with its own pollen, and also with pollen 

 of paniculata and perenms, in equal proportions, produced 

 plants which were all ordinary rustica, and had taken nothing 

 from the other two. Another flower of N. rustica^ pollinated with 

 equal portions of its own pollen and pollen of N. perennis^ gave 

 plants which were ordinary rustica, without any trace of peren- 

 nis. A flower of A'^. rustica, pollinated with 



"a very small quantity of its own pollen, and a much greater amount 

 of the pollen of paniculata," produced "six true hybrids, of precisely 

 the sort that one is accustomed to get from rustica 2 and paniculata S •" 

 (p. 122.) 



Kolreuter investigated the probable nature of the stigmatic 

 secretion, whether it were the female fertilizing substance or not. 

 Removing the secretion from the stigmas of Nicotiana rustica 

 with a piece of blotting paper, he pollinated the surface with its 

 own pollen, and added the stigmatic secretion of A^ paniculata^ 

 getting as a result six plants simply rustica. From another flower 

 of the same plant, pollinated with its own pollen, to which the 

 secretion from A^. mai. vulg. was added, he obtained four plants 

 of ordinary rustica^ with none of the characters of the other 

 species. A flower of A'', paniculata^ pollinated with its own pollen, 

 to which the secretion of rustica had been applied, gave four ordi- 

 nary paniculata plants. Upon the stigmas of a hybrid paniculata 

 ? X rustica $ and another of rustica 5 X paniculata $ , polli- 

 nated with its own pollen, with the addition of the stigmatic secre- 

 tion of paniculata^ he obtained plants which all in appearance ap- 

 proached more the paniculata parent. 



The result of all these experiments led Kolreuter to conclude : 



"That one would almost sooner have reason to hold the female secre- 

 tion to be a mere innocuous conduction medium, than as a true fertilizing 

 material." (p. 128.) 



