III. POLLINATION AND NATURAL CR0S8-FERTILIZATI0N. 



Pollination. 



The method of pollination in Nicotiana rustica has been 

 studied by several observers. Conies' considers this species to be 

 self-fertile. Fruwirth,^ who obtained good setting under nets, 

 states that self-pollination takes place as the flowers open. 

 This is brought about by the bursting of the four long stamens 

 over the already receptive stigma. After the flowers open, the 

 stamens elono^ate and are lifted still further above the stig-ma. 

 Fravvirth and Comes consider, however, that cross-pollination is 

 also possible by means of insects. It appeared therefore that 

 the mode of pollination normally occurring in this species, is 

 self-pollination in the bud brought about by the position of the 

 bursting anthers just above the receptive stigma and that cross- 

 fertilization is rare. 



While studying the various Indian types of this species at 

 Piisa, it was observed that in type I some of the flow'ers dropped 

 ofl" after the fading of the corolla and very few capsules naturally 

 set seed. In this row practically no seed was obtained under bag- 

 in the ordinary way. On examining the buds it was found in 

 nearly all cases that the styles were much longer than the 

 stamens and often protruded beyond the still closed bud. Type 

 I had therefore long styled flowers, and it was found necessary in 

 this case to artificially self- fertilize the flowers in order to obtain 

 seed under bag. 



It now appeared desirable to examine the flowers of the 

 other types of this species. It was found that the anthers always 



^ Comes, JRindiciuito dc/In Ilralc Arcudtniia dclh' Sritiizv fiairlie c iiKitcniatichr di yajwli, 

 Feb. 1871). 



2 Fruwirth, Die Zuchtumj dcr landivirtschaftliihcn Kultiirjijfanzen, Bd. Ill, 1906, s. 89. 



