Hugh Hamshaw Thomas

Hugh Hamshaw Thomas FRS (born May 29, 1885 in Wrexham , Denbighshire , Wales , † June 30, 1962 in Cambridge , England ) was a British paleobotanist who carried out fundamental research on the seed ferns of the Mesozoic Era and the evolution of plants . Its botanical author abbreviation is " HHThomas ".

Life

The early years

Downing College

Hugh Hamshaw Thomas was born the second son of Thomas Walker and Elizabeth Lloyd. He spent half of his childhood in Wales, first went to a small private school and attended from 1904 the Downing College of the University of Cambridge to there Biology study. In his spare time he roamed the spoil heaps of the coal mines in the area collecting fossils , an interest that was awakened by a book present from his father. Although he took a basic course in botany , he did not go through any additional training in this subject other than a few lectures in the advanced course, which he later heard. He did not attend courses in geology at all, because his parents intended him to train as a civil servant and took history as a major. Nevertheless, he worked alongside college with botany and published his first botanical work in the Philosophical Transactions of the Royal Society as a college student.

When he finished his studies in 1908, he decided not to pursue a civil servant career even though he had acquired the qualification, and he fought for the next few years with tutoring and in-depth lessons, while in his spare time he continued to collect fossils and do some scientific papers published. He carried out the necessary work for this at the Sedgwick Museum , in collaboration with or under the guidance of his mentors , Albert Charles Seward and Edward Alexander Newell Arber (1870–1918). In 1909 he got the position of curator at the Botany Institute of Downing College, so that he finally had a small but steady income. In 1912 he was also assistant professor of botany at Trinity College and was able to give up tutoring. In 1914 he was finally elected a Fellow at Downing College, a permanent position that eventually guaranteed him financial independence.

University, family and the world wars

At the beginning of World War I , he joined the Officers Training Corps and was assigned to the artillery in France in 1915 . Shortly before the Battle of the Somme he received orders to march to Egypt , where he was deployed as an artillery supply officer in one of the Suez Canal's defensive zones. After moving to the Royal Flying Corps , he was the commanding officer of a unit that took aerial photographs . Because of his military merits, he was awarded the Egyptian Order of the Nile and the Military MBE .

In 1919 he returned to Cambridge, lived for a few years at Downing College and in 1920 became dean of the college. In 1923, after receiving his license to teach, he began teaching university lectures in various fields of botany. In the same year he married Edith Gertrud Torrence, with whom he had two children. In 1927 he received his doctoral degree ( Doctor of Science , Sc.D. ) and became the governor ( Steward ) of Downing College appointed, a title he held for 17 years. During World War II he joined the Royal Air Force Volunteer Reserve , the organization of the Royal Air Force's reservists . Here, too, he dealt with aerial photography, among other things, and developed a detailed analysis of the Peenemünde facilities . In 1943 he resigned from the Royal Air Force for health reasons. In the following years, in addition to the publication of many scientific, historical and epistemological articles, he was very active in supporting scientific associations and chairing a number of scientific societies. Hugh Hamshaw Thomas died in Cambridge on June 30, 1962.

Scientific work

1910–1925: Thomas and the Caytoniales from Yorkshire

Cycas circinalis , a modern representative of the cycads

On Seward's advice, Thomas began studying the Yorkshire Jurassic plant fossils around 1910, focusing on microscopic examination of the plant cuticle and reproductive organs. He did pioneering work in this area, which was hardly explored at the time. He realized that the Yorkshire Jurassic plant fossils could be divided into two groups due to the structure of their cuticles, the Bennettitales on one side and one similar to today's cycads on the other. In 1913 he published together with Helen (Nellie) Bancroft a landmark work on the links in the structure of the cuticle of fossil and modern cycads ( On the cuticules of some Recent and fossil cycadean fronds ), and began primarily with the order of caytoniales to employ, an extinct plant group of the seed ferns (Pteridospermae), which in some features showed similarities with today's flowering plants .

His work on plant cuticles was just the beginning. The preparation of such fossil tissues is relatively simple: the carbonized tissue is oxidized and dissolved with acid , leaving the cuticle. However, this method destroys all other structures that are still preserved in the fossil. In addition to being interested in the cuticle, Thomas wanted to study the other parts of the plants, especially their seeds . He tried modifications to the acid technology, boiled them in alcoholic potash , made thin sections of it and tried everything to make the internal structures visible. To his disappointment, some of the preparations were excellent, others just a structureless mass: he could not reliably repeat the good results. Later studies have shown that the seeds of the Caytoniales in particular differ greatly in their preservation in one and the same fossil. Despite these failures, he developed a number of basic preparation techniques and gained essential knowledge about the Caytoniales . He published his results in 1925 in The Caytoniales, a new group of angiospermous plants from the Jurassic rocks of Yorkshire , which is considered to be his most important work.

1925–1930: Thomas and Umkomaasia from Natal

Fossil Samenfarn from the Carboniferous of Ohio

With his work he made some enemies because he opposed the predominant, purely descriptive analysis of plant structures by assigning names to the structures described, which determined their function. In his work on the Caytoniales, this was the case with the seed-bearing structures: he called the sac-like seed containers gynoeceum and the branched organs that carry the seed containers he called sporophyll : both terms that are exclusively attributed to the covering seeds. Even if he did not believe that he had found the previously unknown ancestors of the flowering plants here, the protests of his specialist colleagues drove him to open resistance. As a result, however, he failed to prove the proximity of the Caytoniales to the Bedecktsamern, and he turned to other research areas.

Thomas made several trips to South Africa and collected well-preserved pteridosperms from a site in the Triassic of Natal . The leaves found there had been known for a long time, but in his 1933 work On some pteridospermous plants from the Mesozoic rocks of South Africa he also described branched, pollen and seed-bearing parts of plants ( Umkomaasia and Pteruchus ), which he simultaneously had both with leaves and compared to twigs by placing them near pteridosperm sporophylls as well as those of a kitten like that of the poplar . This concept shakes the foundations of descriptive morphology that go back to Goethe , which so far has not taken into account an evolution from a few basic forms and thus the relationship of similar plant parts in different plant groups.

1930–1960: Thomas and evolution

Reconstruction of Rhynia gwynne-vaughanii

In the following years several essays appeared in which he developed the concept of plant evolution based on the theories of Walter Zimmermann . Starting from the from the Scottish Rhynie chert known order Rhynia he ordered the different plant parts of higher plants different parts of the shoot system of Rhynia to. In his view, every plant organ is a telome or a group of telomas, and so there is no essential difference between the organs of different groups of plants.

The consequence of his theoretical-philosophical reflections and publications was the fact that he found little time to deal with the description of plant fossils. He dealt with the history of botany, organized exhibitions of old scientific instruments and gave lectures inside and outside England, for example on Richard Bradley , who in the 18th century developed ideas that were far ahead of his time, but whose importance was given by his successor had been successfully undermined.

Honors

In 1923 he received the Walsingham Medal from Cambridge University. In 1934 Thomas was elected a Fellow of the Royal Society . As a co-founder of the British Society for the History of Science in 1947, he was for many years its chairman and founding member of a number of other scientific associations. He was chairman of several scientific societies, such as the Linnean Society of London . In 1958, as part of the Darwin - Wallace year to celebrate the centenary of the theory of evolution , he was elected one of the 20 biologists who had made the most important contribution to the knowledge of evolution. In the same year he received the Darwin Wallace Medal of the Linnean Society and two years later their Linné Medal . The fossil plant genus Thomasiocladus Florin is named after him.

literature

• TM Harris: Hugh Hamshaw Thomas. 1885-1962 . In: Royal Society (Ed.): Biographical Memoirs of Fellows of the Royal Society . tape 9 . London 1963, p. 287–299 ( online version [PDF; 1.8 MB ]).

Individual evidence

1. ↑ Harris 1963, p. 293
2. ↑ Lotte Burkhardt: Directory of eponymous plant names - Extended Edition. Part I and II. Botanic Garden and Botanical Museum Berlin , Freie Universität Berlin , Berlin 2018, ISBN 978-3-946292-26-5 doi: 10.3372 / epolist2018 .

Web links

• Author entry and list of the described plant names for Hugh Hamshaw Thomas at the IPNI