Page:Makers of British botany.djvu/231

 Rh the nucellus of the ovule which he took to be naked, missing the very slightly indicated integument. He followed the pollen tube to the tip of the embryo-sac and the development of the endosperm in its upper portion, where the embryo appeared. He saw the growth of the endosperm leading to its complete protrusion from the ovule and inverting the embryo so that its cotyledons point to the surface. Further he saw the long, empty, absorbent caecum grow out from the hinder end of the embryo-sac into the massive base of the young seed.

This account is substantially correct in all its facts, and Treub's work adds to it the cellular details of the origin of the embryo-sac, the setting apart of the endosperm cell to grow into the haustorium, and the details of segmentation of the embryo.

Such vivid, accurate, description of strange facts, when previous knowledge gave no clue, is in itself no mean scientific achievement.

To sum up Griffith's work on the morphology of the reproductive organs of the Angiosperms we see that he added many important facts and gave correct descriptions of what still remain among the most anomalous ovules and embryos. His methods did not enable him to distinguish clearly the contents of the embryo-sac, and he accepted and confirmed Schleiden's erroneous view of the origin of the embryo. But this hardly detracts from the directness and consequent value of all his observations.

Turning now to the Gymnosperms, we find again that Griffith devoted much attention to those forms that from his residence in the tropics he was in a position to study with most advantage. He describes in the Notulae his observations on the ovules and pollination of various Coniferae and Gnetaceae. But we may concentrate our interest on his work on Cycas. The rough structure of the young seed had already been described by Robert Brown who had recognised the gymnospermy of the group.

But Griffith's descriptions and figures are much more accurate—are indeed far in advance of those of much later observers—and add greatly to our knowledge of this plant. These two figures (pl. XVI) will speak for themselves and show how clearly Griffith