As regards both Pteridosperms and Gymnosperms proper, attention may be specially called to his work on isolated seeds, in which he was surpassed by Brongniart alone. This field of investigation, long neglected, has lately been revived with striking results.
I hope that all students of fossil botany will have at least turned over the pages and the plates of Williamson's works, for only by inspection of the original memoirs can any idea be gained of his vast services to our science.
His remarkable skill as a draughtsman (for all his memoirs are illustrated by his own hand) is not always done justice to in the published reproductions as the fine examples of his original drawings, so kindly lent for the lecture by Mrs Williamson, will show[131]. At the time when Williamson's main work was in progress—from 1870 to 1892—geologists were probably more appreciative of its value than botanists. Happily, in spite of occasional trouble with Referees, none of his work was lost, the Royal Society going steadily through with all the nineteen memoirs which were entrusted to them.
The one botanist, who, up to the year 1890, estimated Williamson's work at its full value was Count Solms-Laubach, who makes the honourable boast that he knew Williamson's collection as no one else did.
Williamson's writings are not easy reading, especially for the modern botanical student, for the terminology is often unfamiliar, and the arrangement of the matter unsystematic.
It would be out of place to enter on a criticism of details, but it is necessary to call attention to the one serious mistake which ran through much of Williamson's work, though at the last he to a great extent corrected it himself. He was always too ready to interpret specimens of the same fossil plant which differed in size and anatomical complexity, as developmental stages of one and the same organ. Such differences among fossils are more often due to the order of the branch on the plant, or to the level at which a section is cut. This error led to some mistaken, and indeed impossible views of the process of development. I mention this partly because I have noticed the same fundamental mistake in the work of much more modern writers. "We are none of us infallible—not even the youngest of us," and among the latest fossil-botany papers I have read, I have detected the very same confusion between differences of size and differences of age, which constitutes the most serious blemish in Williamson's writings.
As is well known, Williamson in his latest independent work corrected, as regards the Lepidodendrons, on the basis of a laborious re-investigation, the chief mistake he had made as to their process of growth[132]; he thus displayed an openness of mind worthy of a great naturalist.
I first saw Williamson on February 16, 1883, when I attended his Friday evening lecture at the Royal Institution, "On some anomalous Oolitic and Palaeozoic Forms of Vegetation." I did not, however, make his acquaintance till six years later, when we met at the British Association Meeting at Newcastle-upon-Tyne, in 1889. This led to a visit to his house in company with Prof. Bower; it was on March 8, 1890, that I first had a sight of his collection. I find the entry in my diary: "Spent 7 hours over fossils, especially Lyginodendron and Lepidodendron, preparations magnificent." I at once became an ardent convert to the cult of fossil plants to which I had hitherto been indifferent, though I must in fairness admit that Count Solms-Laubach's Einleitung had done something to prepare the way. I well remember the state of enthusiasm in which I returned home from Manchester. A subsequent visit confirmed me in the faith, but it was some little time before I put my convictions into practice. In 1892 Williamson, then in his 76th year, resigned the Manchester Professorship and came to live near London. In the same year I migrated to Kew, and it was agreed that we should work in concert, an arrangement which received every encouragement from the then Director, Thiselton-Dyer. Williamson first came to the Jodrell Laboratory on Friday, December 2, 1892. Then, and on many later visits, he carried a satchel over his shoulder, crammed with the treasures of his collection. For some months he came pretty regularly once a week, afterwards less often. On these visits we discussed the work I had done on the sections during the interval, and sometimes our discussions were decidedly lively. In the end, however, we always managed to come to a satisfactory agreement. Our first joint paper (Calamites, Calamostachys and Sphenophyllum) was sent off to the Royal Society, rather more than a year from the start, on December 29, 1893.
During the early part of 1894 Williamson came occasionally to Kew, and our discussions were renewed, this time chiefly on Lyginodendron. Our second paper (Roots of Calamites) was despatched on October 30, 1894.
After a considerable interval Williamson again visited Kew, on December 12, 1894, when we started on his Lepidodendron sections, a subject on which we never published in conjunction. His last visit was on January 7, 1895. A few days later his health broke down, and though there were many fluctuations he was never able to come to the laboratory again. I saw him last, at his own house, on June 4th. On the 13th I read our joint paper on Lyginodendron and Heterangium at the Royal Society; on the 23rd he passed peacefully away.