88 HETEROSTYLED DIMORPHIC PLANTS. Chap. IIL 



and this was a very short one. To make sure that the 

 pollen was good, I took in this ease, and in most of 

 the other cases, pollen either from the same anther or 

 from the same flower, and proved it to be good by- 

 placing it on the stigma of a short-styled plant, and 

 found numerous pollen-tubes emitted. 



Thirdly. Eepeated last experiment, and placed own- 

 form pollen on all five stigmas of a long-styled flower; 

 after nineteen hours and a half, not one single grain 

 had emitted its tube. 



Fourthly. Eepeated the experiment, with the same 

 result after twenty-four hours. 



Fifthly. Eepeated last experiment, and, after leaving 

 pollen on for nineteen hours, put on an additional 

 quantity of own-form pollen on all five stigmas. After 

 an interval of three days, the stigmas were examined, 

 and, instead of being discoloured and twisted, they 

 were straight and fresh-coloured. Only one grain had 

 emitted a quite short tube, which was drawn out of 

 the stigmatic tissue without being ruptured. 



The following experiments are more striking: — 



Sixthly. I placed own-form pollen on three of the 

 stigmas of the long-styled flower, and pollen from a 

 short-styled flower on the other two stigmas. After 

 twenty-two hours these two stigmas were discoloured, 

 slightly twisted, and penetrated by the tubes of nu- 

 merous pollen-grains: the other three stigmas, covered 

 with their own-form pollen, were fresh, and all the 

 pollen-grains were loose; but I did not dissect the whole 

 stigma. 



Seventhly. Experiment repeated in the same man- 

 ner, with the same result. 



Eighthly. Experiment repeated, but the stigmas were 

 carefully examined after an interval of only five hours 

 and a half. The two stigmas with pollen from a short- 



