Part 32

The Loranthaceae was another family on which the development of the embryo-sac and the processes of fertilisation and development of the fruit interested Griffith specially. Not only did he send his results home to the Linnean Society in two papers, but his descriptions and figures of all the species described in the Notulae take account of these morphological and developmental facts. He traced the development of the cavity of the ovary and regarded the ovules as reduced to their simplest expression--to an "amnios" or embryo-sac. And he observed the extension of the embryo-sacs up the style and the union of the pollen tube with the tip of the embryo-sac. His further description of the development of the embryo, endosperm and fruit is wonderfully exact if we allow for his regarding the long suspensor bearing the embryo as derived from the pollen tube growing down through the long embryo-sac.

Griffith thus recognised all the main peculiarities of Viscum and of Loranthus subsequently described more in detail in European species by Hofmeister (whose analysis of Griffith's work in 1859 is a great testimony to its accuracy) and later by Treub in the tropical species which had been studied by Griffith.

The Balanophoraceae was another group, on which Griffith made pioneer investigations. He collected and examined all the species he met with, partly from the systematic interest in supporting Robert Brown's objection to Lindley's class of Rhizantheae, but still more from his interest in the details of their reproduction. An examination of the plates from his memoirs, only published after his death, in the Linnean Transactions will show how fully he was aware of the structure of the archegonium-like female flower of Balanophora; of the relation of the pollen-grains and pollen tubes to it; and of the appearance of the endosperm which he mistook for the embryo. Throughout he compares the structure with the pistillum (archegonium) of Bryophyta.

Thus in the Balanophoraceae also Griffith laid the foundations on which the work of Hofmeister, and more recently that of Treub and Lotsy follow.

When at Malacca Griffith interested himself among many other problems in the ovule and the development of the seed of Avicennia. He had previously paid attention to the viviparous embryos of other Mangroves. This piece of work, when compared with Treub's re-examination of Avicennia, brings out so clearly Griffith's accuracy, so far as his means of observation allowed him to go, that we may look for a moment at how these two investigations, separated by forty years, compare.

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.

From what has been said of the nature of Griffith's work on the ovules, both of Angiosperms and Gymnosperms, the complete omission of his name in recent works on the two groups that are in constant use is at least noteworthy.

Griffith was specially interested in the study of Cryptogamic plants. In a letter to Wight he says "I would like to be out with a work on Indian Cryptogamia of higher forms; so much so that if I see no chance of my succeeding to the Gardens, I intend sending away all my other collections, and devoting myself to this object and general development, which is obviously the keystone of the arch."

He left Algae and Fungi (with the exception of the Characeae) alone, and it is his work on the Bryophyta and Pteridophyta that concerns us. For information on his views on these plants we are dependent on his paper on Salvinia and Azolla and on the Notulae, put together as I have said from his notes after his death, and not intended for publication in this form. But there is no difficulty in getting a clear grasp of his point of view. This was a mistaken one--an attempt to bring into line the reproduction of the gametophyte of Bryophytes, the sporophyte of Vascular Cryptogams, and the flowering plant with its flower and fruit. It is easy to be wise after the event. In these comparisons Griffith belonged to his time with a much wider field of personal observation than most possessed.

Median section of the ovule of Cycas

Nucellar apex of Cycas with pollen chamber and pollen grains]

We must bear in mind that at the time when Griffith worked no idea of the sexual and asexual alternating generations in Pteridophytes had been gained, although the prothallia had been observed preceding the growth of the plant in Equisetum and Ferns. It was not till some years after Griffith's death that fuller facts as to the sexual organs were obtained and led to the right comparisons.

Griffith's work on the Bryophyta shows the same power of observation as that on the ovule, but the difficulties due to imperfect instruments are more evident. His views on reproduction were here, however, clear, since the development of the capsule was definitely related to the fertilisation of the pistilla (archegonia) by the substance formed in the anthers. His figures indicate how much he saw, and how here also he sought in development the interpretation of mature structure.

His early interest in the Liverworts, especially the Marchantiaceae, continued, and all the forms he collected were carefully examined and figured with his usual accuracy.

One of the Liverworts Griffith described may be taken as an illustration to this part of our subject on account of the interest of its re-discovery and re-description in 1910 by Goebel. This is a plant collected in Assam and named Monosolenium tenerum. This Marchantiaceous plant is described as having no air-chamber layer, as bearing sessile, dorsal, antheridial receptacles, and terminal, shortly stalked archegoniophores with one ventral groove in the stalk. A single archegonium--later capsule--is found in each of the half-dozen involucres. Spores and irregular bodies were found in the capsule.

Recently Goebel had two tea-plants sent home from Canton. They died, but he kept the soil moist on the chance of germinating seeds. Among a number of other plants there turned up a new Liverwort. On examination this proved to be Griffith's Monosolenium--all types of which had been lost--a most interesting form related to the Corsiniaceae.

In the Mosses and the Liverworts generally Griffith was clear on the development of the capsule or fruit following on the impregnation of an archegonium. But in Anthoceros, while he recognised the antheridia he was not clear as to the sunken archegonia, and regarded the capsules as arising by impregnation of unrecognisable spots on the young frond or thallus. He observed however the indication of the canal of the archegonial neck above the young capsule.

Analogy with Anthoceros confirmed him in his views on the reproduction of ferns. Here he spent much labour in considering the view, originally due to Hedwig, that the ramenta were male organs by the effect of which the sporangia developed. Griffith saw that if this was so, since the sporangia are initiated very early, the only time to search for the male organs was in the very young stage of the leaf. On examining such young leaves he found the terminal cells of the young ramenta very prominent and formed the working hypothesis that they were the male organs. But he stated this cautiously and was well aware how imperfect his means of observation were.

The whole line of work brings vividly before us how cryptogamic the Cryptogams were at this period.

Without attempting to survey Griffith's views on the various groups of Vascular Cryptogams, a word must be said of those on Salvinia and Azolla, on which he published a long paper in addition to the other descriptions and figures in the Notulae. His observations bear on the development of the sorus and sporangium, but he dismissed the microsporangia as abortive or imperfectly developed structures. (I may note in passing that the study of their development led him to regard the microsporangia of Isoetes in the same way.) He dwelt on the similarity of the sporangium and indusium of Azolla to a gymnospermus ovule, and regarded the filaments of Anabena seen penetrating within the indusium as probably the fertilising bodies in this naked-seeded cryptogam.

Thus with a large amount of fresh and original observation Griffith was on wrong lines in his general views and comparison--he classed the higher Cryptogams in his Notulae as

Pistilligerous. Musci. Hepaticae. Gymnospermous. Azolla. Salvinia. Chara. Cryptogamous. Ferns. Lycopods. Isoetes. Marsilidae. Anthocerotidae. Equisetidae.

Griffith's general views of the reproduction of all the Vascular Cryptogams was necessarily wrong, since the prime clue of the recognition of the prothallus and plant as distinct had not been found. In this connection his figuring young plants of Equisetum attached to prothalli is interesting. In some speculations concerning the embryology of Loranthus he came, by a wrong line of approach, within touch of the right comparison, when he compares the endosperm to the confervoid green growth (i.e. the prothallus) at the base of the young plant of Equisetum.