of it can be observed; I imagine that in such cases it 

 has so far degenerated, that it can no longer be rendcred 

 visible. Yet another hypothesis miglit be suggested, na- 

 mely, that thèse nuclei fuse like two polar nuclei. I regard 

 this, however, as extremely improbable, for the very reason 

 that the two nuclei are so clearly in a state of de- 

 generation. Indeed, ail the rest of the embryo-sac does 

 not come to much; endosperm is not fonned; the cell is 

 still seen for some time, until it disappears with the 

 developing embryo. 



For some time the egg and the synergids undergo no 

 further changes, and are ready for fertilisation. This process 

 I hâve only been able to follow accurately in Mourera 

 fluoiatilis Aubl ; in a few other cases I found a young 

 embryo, or somotimes pollen-grains, which had germinated 

 on the stigma and had developed pollen-tubes. In a new 

 species of Âpinagia, still to be described, there occur, in 

 addition to the normal hermaphrodite flowers, others, 

 which hâve abortive stamens, and which remain inside 

 the closed spathella, at least as far as I hâve been able 

 to observe in the material at my disposai. Whether the 

 latter flowers can also furnish ripe seeds, without ferti- 

 lisation, I cannot say, as they had not developed beyond 

 the stage, hère described. In the numerous préparations 

 of varions Podostemaceae which I hâve examined, I found 

 moreover many ovules, which were degenerating at the 

 above-mentioned stage, evidently because no fertilisation 

 had taken place. It seems to me, that the chance of 

 regular pollination among thèse plants Is probably not 

 so very large, and that in conséquence of this so many 

 ovules ultimately abort. 



I now pass on to describe what I hâve seen of the 

 fertilisation itself, and must remark, that I hâve but 

 rarely observed anything of the pénétration of the pollen- 



