Makers of British Botany; a collection of biographies by living botanists
History
Makers of British Botany; a collection of biographies by living botanists
Botanists -- Great Britain -- Biography; Botany -- Great Britain -- History
Griffith recognised the development of the embryo-sac in 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 had grasped the
morphology of the Cycadean ovule, how faithfully he delineated the
details, and how he sought in progressive development to throw light
on the structure. He added to the previously imperfect description of
the ovule an accurate account of the pollen chamber, and the proof
that pollen grains entered and filled it. Further he followed the
germination of the pollen grains, not merely recording the fact that
the tubes penetrated the nucellus all around the pollen chamber, but
ascertaining in how many days the tubes were put forth. His fullest
description is unfortunately displaced in the _Notulae_ under the
heading of _Thuja_, but it is clear that it refers to the _Cycas_
figured on the same plate as that plant.
Public-domain text, read in full here on John Shaqi.
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