402 SLOWNESS OF FECUNDATION. 



the process would change color when placed on the 

 surface ; but that the more distant the relationship, 

 or (as Herbert expresses it) the affinity, the greater 

 was the amount of pollen required ; and as the 

 relationship was more or less distant, was the pro- 

 portion of perfect seeds procured ; — with the most 

 distant, the least number. He thought that the 

 life, or sensitiveness, of the stigma was longer when 

 fertilized by foreign than by its own pollen. This 

 change of the stigma was at very different periods 

 in natural fecundation, from eighty-five minutes to 

 several hours ; that it probably merely saturates 

 the stigma in that time, and does not really fertilize 

 the germen. He reasons that, " if the fertilization 

 was complete, and the office of the stigma defunct, 

 it might be cut off without any detriment, unless 

 necessary to the mere nourishment of the ovules, 

 whether fertilized or not, which does not seem 

 probable; but I have repeatedly cut it off a few 

 days after I had applied pollen to the rhododendrons, 

 and the result has been that no seed was formed. 

 The whole of my observations have led me to think 

 that, at any period before the decay of the stigma, 

 the access of the natural pollen may supersede the 

 influence of the foreign that may have been pre- 

 viously applied, if not from a closely allied species 

 or variety ; but that, on the other hand, no foreign 

 pollen can act upon the germen after the stigma 

 has been fertilized naturally. The incomplete sat- 



