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Adam Sedgwick

Professor Adam Sedgwick by William Strang, RAAdam Sedgwick (1854-1913) was brought up in Dent, Yorkshire, where his father was vicar. Both his father and his mother belonged to local landowning families. Adam Sedgwick, zoologist, shares his name with the much better known Adam Sedgwick, clergyman, geologist and mentor of Charles Darwin, and after whom Cambridge's Sedgwick Museum is named. The two Sedgwicks were related; the zoologist was the great nephew of the geologist. Both became FRS (Sedgwick the zoologist was elected in 1886).

Zoology's Adam Sedgwick seems now to be rather poorly remembered within the Department, yet he served as the second Professor of Zoology, succeeding Alfred Newton in 1907. Sedgwick supported the teaching of morphology in Cambridge over much of the period of Newton's Professorship, while Newton concentrated on systematics. There appears, however, to have been no tension between the two, and, as one of Sedgwick's obituarists comments, ''He lived also in the most friendly and harmonious relations with Newton, Professor of Zoology in Cambridge, who, instead of regarding the development of the newer side of zoology with suspicion or jealousy, aided and abetted Sedgwick in every possible way.' The brevity of Sedgwick's tenure of the named chair probably accounts for his relative obscurity: he left to become Professor of Zoology at Imperial College, London in 1909. However, in Cambridge he held a Lectureship, in Animal Morphology from 1883-1890 (for which he received £100 per annum), and a Readership, again in Animal Morphology, from 1890-1907; so he had fourteen years of employment in the Department before taking up the Professorship. Sedgwick became a Fellow of Trinity College in 1880, and he had taken his BA and MA degrees (in 1877 and 1881) at Trinity after education at Giggleswick School and Marlborough College, and a brief period at King's College, London (with the intent of studying medicine). He also served as a Tutor at Trinity from 1897 until he took up the Cambridge chair. Several of Sedgwick’s obituarists offer the opinion that his research work effectively ceased when he took up the tutorship at Trinity. Sedgwick's period at Imperial also turned out to be rather brief; he died in office at the age of only 58, having served four years, and those mostly in declining health.

When Sedgwick is remembered now, he is remembered principally for his embryological work on Peripatus. Few today will be aware of his popular and influential textbooks (his Student's Textbook of Zoology was published in three volumes, in 1898, 1905 and 1909, the last with the assistance of J.J. Lister and A.E. Shipley). Sedgwick was a contributor to the famous 1911 edition of the Encyclopaedia Britannica, and many of his contributions survived in later American editions.  He is also known for his devotion to the memory of the embryologist Frank Balfour (1851-1882), with whom he was linked through Trinity. It is clear that Balfour strongly influenced Sedgwick's choice of research area, as did the physiologist Michael Foster (a powerful force in Cambridge zoology, and who had been a pupil of T.H. Huxley). When Balfour died at just 30, it was Sedgwick who became a central figure in the coalition of embryologists and morphologists established and made famous by his inspirational mentor; and it was Sedgwick who took over Balfour's rooms in a new building on the New Museums Site, completed in 1882 shortly before Balfour's death. Shortly afterwards, Sedgwick, keeping with the spirit of Balfour, recruited further demonstrators in morphology and embryology, and also took on W.H. Caldwell and Richard Threlfall, both of Caius, who were pursuing the development of the 'automatic' microtome. In 1941, H. Munro Fox, writing in Nature considered the history of the development of the microtome, and refers to the account by Threlfall, noting that, 'Threlfall's article includes a photograph of a copy of the original instrument; this copy is now in the Science Museum, London. The original instrument is in the Zoology Department, Cambridge.' It still is, and can be seen in a display case on the second floor of the Department.

Sedgwick shared equipment, largely microscopes, with Foster, and this created some difficulties, particularly for teaching. Both men used these difficulties to their advantage, however, and shortly after University discussions in 1884 Sedgwick took delivery of one hundred Zeiss microscopes (at an advantageous price of £7 each). The fascinating account by Helen Blackman (Journal of the History of Biology (2007) 40:71-108), from which I have taken some of the information in this short biographical sketch, gives as its Table 1 a list collated from the Cambridge University Reporter of courses in zoology advertised between 1866 and 1900. The list reveals that between 1883 and 1899 Sedgwick taught courses on invertebrate morphology at both elementary and advanced levels, and on embryology, mostly of invertebrates but with consideration of vertebrates as well. From 1888-1897, he taught elementary biology together with Francis 'Frank' Darwin (son of Charles Darwin). Sedgwick taught the zoology and Darwin the botany. Sedgwick also taught several of the courses alongside other lecturers, including S.F. Harmer (1862-1950), Superintendent of the Museum of Zoology from 1892-1908, but, interestingly, not alongside Frank Balfour, himself. In a section on 'Animal Morphology after Balfour', Helen Blackman gives a revealing account of the tension that developed between William Bateson, who in 1899 was teaching a course under the title 'Practical study of evolution', and Sedgwick. In essence, Sedgwick was perceived as continuing Balfour's morphologically based work but without adopting the experimental approaches being developed on the Continent, notably in Germany. Bateson, a pioneer in genetics, who emphasised variation in his research, had strong reservations about hypotheses of phylogenetic relationship based on morphology, and particularly those based on comparative embryology. In some measure, Sedgwick was drawn to agree with these doubts, although he defended the study of comparative morphology in public with characteristic robustness. As Helen Blackman puts it, 'Sedgwick lost faith in comparative embryology, but retained his faith in morphology'.

When Sedgwick became Professor of Zoology in 1907, it was Bateson who was appointed, rather reluctantly on Bateson's part, to the Readership vacated by Sedgwick. Not surprisingly, the title of the Readership was changed from Animal Morphology to Zoology; but, nevertheless, Bateson left a year later for the John Innes Institute, a more congenial base for the work that he was pursuing. Shortly after Bateson's departure, the Department of Zoology underwent reorganisation, and the governance of the Museum of Zoology was substantially transferred to its Superintendent. Sedgwick, who was known to be unhappy to have lost some of his authority, resigned in 1909, and made the move to Imperial College. Helen Blackman also documents the transfer of vertebrate embryology in Cambridge to the Department of Anatomy, as part of the changes around this time, shortly after the appointment of Adam Sedgwick's successor, J. Stanley Gardiner, leaving invertebrate embryology to Zoology. When at Imperial, Sedgwick recruited the vertebrate embryologist Richard Assheton, ex-Trinity and a former student of Sedgwick, and who subsequently returned to Cambridge Zoology to a post created for him in 1914 by Stanley Gardiner. So there was a two-way traffic between Cambridge and Imperial, but with the common factor of Trinity!

For sources of information, Marsha Richmond's 2013 entry in the Oxford Dictionary of National Biography provides a concise account of Sedgwick (an account duplicated on the website of Trinity College), and both Nature and The Times published unsigned obituaries of Sedgwick in 1913. Two other obituaries of Sedgwick are, however, especially helpful in providing information about Sedgwick's work, and in forming an impression of the personality behind the professional man. Sedgwick's death came before the Biographical Memoirs of the Royal Society were established, but at that time obituaries of Fellows were customarily published in the appropriate volume of the Proceedings. The account of Sedgwick's life (Proceedings B, LXXXVI) is initialled E.W.M. This was clearly Ernest William MacBride (graduated in Cambridge, 1891), Professor of Zoology McGill University, Canada (1897–1909) and successor to Sedgwick as Professor of Zoology at Imperial College, London (1913–1940). MacBride had been taught by Sedgwick, and tactfully passes over the tensions in Cambridge that appear to have contributed to Sedgwick's move to Imperial. (On grounds of style and content, MacBride is very probably also the author of the shorter obituary in The Times.)

MacBride observes that, 'Though his studies as a scientific man led him to radical views on many subjects, those who knew him best were never in any doubt as to the existence of an underlying stratum of conservativism on social, religious, and political matters, which formed, so to speak, the bed-rock of his mind.'  MacBride continues, 'In reviewing Sedgwick's contributions to science, his eager and ardent nature must be constantly borne in mind. Hence he was forever seeking new points of view and was apt to be somewhat impatient of those who clung to older views. He was wont to state his ideas in somewhat strong language, which roused opposition and delayed recognition of the side of the truth which he was seeking to emphasize... He had a hasty temper which used to relieve itself in a somewhat violent language with a plentiful admixture of expletives but the storm was over almost as soon as it arose, and the expletives left no sting behind…' However, MacBride is also at pains to emphasise the high degree of affection in which Sedgwick was held by his students and friends, and that he was a loyal and supportive colleague.

The second major obituary of Sedgwick is, not surprisingly, that by J. Stanley Gardiner, his successor as Cambridge Professor of Zoology, in The Zoologist. It is a characteristically astute and complete account, and substantially agrees with MacBride's in its evaluation of Sedgwick's scientific legacy and his personality.

Sedgwick did indeed have strongly held, and strongly expressed, opinions on a number of fundamental ideas in zoology, such as the development of the vertebrate kidney, prevailing theories about recapitulation, the origins of metameric segmentation, the similarities between the blastopore and the primitive streak, and the cell theory. In the case of recapitulation, although he was originally enthusiastic about what might be termed classic recapitulation, he ultimately came to regard many of the arguments put forward by others, both in favour of the theory and against, as vapid and unconstructive. In print, he was particularly critical of von Baer's ideas, with which he engaged fully, but his relative lack of engagement with Haeckel's work I would interpret as profound disapproval. Certainly, Sedgwick appears to have been astutely and prophetically critical of the accuracy of Haeckel's drawings of embryos. Sedgwick's scientific legacy is undoubtedly dominated by his morphological and embryological studies of Peripatus, but it was also out of this work that his combatively expressed views on the cell theory were derived. The 'cell theory' at its most basic simply held that all living things are made up of cells and that these cellular units have an element of autonomy.  However, the theory was the subject of many accretions, some of them dubious even at the time. One central issue of later cell theory had to do with the evolutionary origin or origins of multicellularity, and whether evidence about this issue is available from embryological studies. Some of the discussions at the time now appear as long irrelevant, but others are surprisingly modern. It is striking, for example, to read Sedgwick's involvement of the structure and behaviour of mesenchyme and of neural crest cells in his arguments.

But it was for his work on the onychophoran Peripatus that Sedgwick received his FRS, and for which he is probably most remembered. Marsha Richmond provides a succinct summary of this work, and I quote from her account now.  'Sedgwick's major research work stemmed from Balfour's earlier study of the aberrant terrestrial tracheate arthropod Peripatus (Onychophora), which attracted interest by exhibiting characters of both annelids (segmented worms) and metamerically segmented arthropods (insects, arachnids, and crustaceans). In 1883 Sedgwick travelled to South Africa, collecting over 300 live specimens of P. capensis. He published a series of papers on the embryology and systematics of this transitional form. Collected together in 1889, they are exemplars of classical zoology, combining careful anatomical and embryological descriptions with considerations of leading theoretical questions. After his research ceased in the mid-1890s Sedgwick returned to these questions in a number of general articles.' Indeed, as time went by, Sedgwick returned more frequently to his work on Peripatus to illuminate almost every other idea with which he engaged: the Peripatus studies were, quite clearly, his golden age. A small selection of recent papers considering the biology of onychophorans is given at the end of this article.

It is gratifying to be able to report that some of Sedgwick's  serial sections, including some of Peripatus, have resurfaced in the Department, to the delight of Michael Akam, the present Professor of Zoology, who has a long-standing research interest in the body plans of arthropods and their allies. The slides are now housed safely in the Museum of Zoology, and represent a tangible legacy of Adam Sedgwick – the zoologist.

 

Mayer, G. & Whitington, P.M. (2009) Velvet worm development links myriapods with chelicerates. Proc. R. Soc. B276: 3571–3579. doi:10.1098/rspb.2009.0950

Campbell, L. I. et al. (2011)  MicroRNAs and phylogenomics resolve the relationships of Tardigrada and suggest that velvet worms are the sister group of Arthropoda. PNAS 108: 15920-15924. www.pnas.org/cgi/doi/10.1073/pnas.1105499108

Janssen, R. et al. (2015) Fate and nature of the onychophoran mouth-anus furrow and its contribution to the blastopore. Proc. R. Soc. B282: 20142628. http://dx.doi.org/10.1098/rspb.2014.2628

Written by Adrian Friday