240 REMARKS ON THE FERTILIZATION OP THE GENUS GOODENIA. 



Soc, Dec, 1884. " When the stigma has grown far above the 

 anthers it exposes a large mass of pollen adherent to it, it does 

 not fall into the corolla, but is carried away (presumably) by insects 

 for the fertilization of other flowers. Thus like Lobelia, in the 

 same natural order of plants, it first ofiers its own pollen for the 

 fertilization of other plants, and then exposed its own stigma to 

 receive that of other plants in return." 



But we may go still farther, and say, that even the fact of pollen 

 tubes being emitted from the pollen grains, does not of necessity 

 imply self-fertilization. Any one in the habit of examining the 

 reproductive organ of plants microscopically, will frequently have 

 found pollen tubes emitted from the pollen grains covering the 

 stigma ; and which, as the stigma is not covered by the cuticle, 

 may even have very slightly penetrated it ; but only to this slight 

 extent, because the stigma is not mature or in any way prepared 

 to utilize it. Pollen may be induced by artificial means to emit its 

 tubes, and will do so of itself under favourable circumstances, 

 ■whether on a stigma or not. As an instance of this, I may say 

 that I had or still have a microscopic slide containing grains of 

 pollen of the common wall-flower (Cherianthus chieri) which I 

 supposed to be quite dry when mounted, but which, from damp 

 and warmth, emitted tubes some days afterwards. In another 

 instance I found pollen on the stigma of Lobelia which had emitted 

 tubes ; but which, not being able to penetrate the unprepared 

 surface, had raised the pollen grains so that they stood up on the 

 face of the stigma like minute pins upon a cushion. I may 

 perhaps add here a caution to young botanists, not to mistake this 

 appearance on the stigma of Wahlenbergia for pollen grains so 

 lifted up ; the surface of that stigma being covered with globular 

 headed glands, very likely so to mislead an inexperienced observer, 

 into the supposition that they are pollen tubes partly penetrating 

 the stigma. 



