Page:Miscellaneousbot01brow.djvu/555

 IN ORCHIDE^ AND ASCLEPIADE.E. 537

��ADDITIONAL OBSERVATIONS ON THE MODE OFiTsy FECUNDATION IN OUCHIDEiE.

Read June 5th, 1832.

The following additions to the Paper which was commnm*- catcd to the Society in November last, on the Sexual Organs and Mode of Fecundation in Orchideae and Ascle- [)iadea3, relate entirely to the former family.

In the essay itself I had ascertained from the examina- tion of a considerable nimiber of species belonging to different tribes of Orchideae, that in the expanded flower of this family, however long it had remained in that state, no appearance whatever existed of those tubes which form the mucous cords, either in the tissue of the stigma or in the cavity of the ovarium, anterior to the application of the pollen to the stigma ; and that in all cases where pollen had been applied to that organ and enlargement of the ovarium had followed, the mucous cords were to be found.

From these facts I had concluded that the tubes forming the cords were entirely and directly produced from the grains of pollen ; and hence I accounted for the cohesion of the pollen into masses, and its frequent application in that state to the stigma.

Some cases, however, in which a few lobules or even grains of pollen only were observed on the stigmata of im- pregnated flowers, had led me to express myself doubtfully on this point. And since my paper was read, I have had opportunities of making several observations and experi- ments which prove that the application of a very small portion of a pollen mass to the stigma is sufficient for the production of mucous cords of the ordinary size in the cavity of the ovarium.

My observations on this point and on the gradual pro- (74<» duction and descent of these cords have been made chiefly on Bonatea sjjcciosa, perhaps the most favom'ablc subject fur such experiments in the whole family.

�� �