G. M. Thomson, — On the Fertilization of Flowering Plants. 283 



perianth) is shorter than the stamens, but, as they open, it lengthens 

 rapidly, and carries the stigma up one side and past the expanding anther- 

 cells. 



Of those which are dioecious in function there are two forms, which, 

 though growing usually side-by-side, are distinct enough to be taken for two 

 varieties. The male or staminate form is considerably larger and more 

 conspicuous than the other. When fully open the two stamens are quite 

 exserted from the perianth-tube. At this stage the slender style, with its 

 minute, almost glabrous, stigma, is only about half the length of the perianth- 

 tube, but, after the anthers have dihisced, it lengthens very much and pro- 

 trudes between the lobes of the perianth, as if to ensure fertiUzation. 

 Having reached this stage further development ceases, the small ovary with 

 its contained ovules, which never become fertilized, commences to shrivel, 

 and ultimately the whole flower withers and falls off. 



The smaller pistillate flowers have a long style, bearing at its summit a 

 capitate stigma, which is so crowded with glandular or papillose hairs as to 

 be almost globose, and which projects at the mouth of the perianth. Nearly 

 half way down the tube are the two minute stamens, with shrivelled anthers 

 containing no pollen. Probably between these two forms, and truly her- 

 maphrodite ones which are proterandrous, there are intermediates. I have 

 not yet found any forms absolutely dioecious in structure, though the species 

 seems tending towards this. I think that in the gradation from the pro- 

 terandrous hermaphrodite form to the staminate form, in which the first 

 part of the proterandry is carried out but the second fails to be carried out, 

 we see the step by which the dioecism (to coin a word) of this plant is 

 attained. 



In all its forms the flowers of this plant are small, but conspicuous by 

 theu' association into terminal corymbs ; they are sweet-scented and their 

 tubes invariably contain honey, so that they must be very attractive to 

 insects. 



Drapetes dieffenhachii has extremely small and rather inconspicuous 

 flowers, which are not crowded into masses as in the preceding species. I 

 could not detect any smell or honey, yet I am inclined to think that this 

 plant is tending in the same direction as Pimelea i^rostrata. There seem to 

 be two forms, in one of which the pistil is very much smaller than the 

 other. I did not make out, however, whether there was a difference of 

 function in the two kinds. They are probably visited by minute Lepidoptera, 

 which swarm in immense numbers among low-growing plants during the 

 summer months. 



In the lower orders of Dicotyledonous plants wind-fertilization is the rule, 

 and, as if effectually to prevent self-ferfcilization, most of the plants belong- 



