Thomas Johnson (botanist)

There were two "Thomas Johnsons" who were both "botanists"

"Thomas Johnson" attended Elmfield College and was Professor of Botany at University College, Dublin from 1890 to 1926.

The other "Thomas Johnson" has been called "The Father of British Field Botany" but has been largely neglected, no doubt largely due to the very scanty recordsof his life which have survived. Such as there are, moreover, in any casesconfuse rather than help the biographer, owing to the popularity of the nameThomas Johnson.

Kew and Powell (1932) describe him as a "learned, amiable, brave man."Their first chapter is devoted to a list of Johnson's publications and of otherworks to which the authors referred during their investigations.

The second chapter provideas a chronologicalaccount of Johnson's life and work. With regard to the date ofJohnson's birth (which almost certainly took place at Selby in Yorkshire, although he is also said to have come from Barton on Humber)the authors are forced to admit that they have not advanced beyond thestatement made by Trimen and Dyer in 1869, that "it was probably at thebeginning of the seventeenth century." His early years are equally obscure,and it is not until the first of his famous journeys (to Kent in 1629), when hewas an apothecary practising at Snow Hill, that we obtain any clear picture ofhis activities. These journeys are here vividly described, and mention madeof many of the plants found by him and his fellow apothecaries. The authorsquote from the "somewhat free" account of the Kentish journeys which appearedin The Phytologist for 1848 Those interested in the byways of Victorianbotanical literature might well read the whole of this article, and especiallythe severe editorial censure called forth by certain passages, harmless enoughto our modem ears, on the refreshment taken by Johnson and his companionsduring their journey (The Phytologist, 3, 125. 1848).From this date (1629) until the beginning of the Civil War, Johnson ledan exceedingly active life, combining his practice as an apothecary with furtherbotanical excursions, and the publication of those works on which his famerests. In the Civil War he fought for the King and was mortally wounded in1644 at the siege of Basing House, in which he distinguished himself by conspicuousbravery and of which the authors give an absorbing account compiledfrom contemporary reports.In the third chapter Johnson's place in the investigation of the BritishFlora is reviewed and it is here that the authors make their most importantcontribution to botanical history. Hitherto it has been generally acceptedthat the first British Flora was How's Phytologza Bvitauc?zica, published in 1650.It is pointed out, however, that Johnson's Mevcz?,vizcs Bota?zicz6s (published intwo parts, 1634 and 1641) contains not only a list of the plants found by himon his journeys in the West of England, but also an enumeration of all thethen known indigenous British plants, and that it should therefore displaceReviewsthe Phytologia, which was largely compiled from it, as the first British Flora.The fact that its claim has been so long overlooked is probably due to itsrarity, and subsequent historians have relied on the statement by Pulteney (whoonly saw one part of the Mevczcvzzcs) that How's was the first Flora of Britain.The final chapter discusses the various genera which have been namedJoh?zso?zia in honour of the subject of this biography.The book is illustrated throughout by drawings and facsimile pages fromJohnson's works and deserves to be widely read by all interested in the historyof British Field Botany. J. s. L. G.The Mechanism of Creative Evolution. By C. C. HURST, Ph.D., F.L.S.Pp. xxi + 364, with a frontispiece and 199 figures in the text.Cambridge University Press, 1932. 21s.Dr Hurst's book gives an account of evolution regarded from a cytologicalpoint of view. It is concerned entirely with the genetic mechanism and makesno attempt to deal with the relations between the organism and its environment,either with regard to the possible origin of mutations or to subsequentselective processes.The first chapters deal with the original genetical and cytological discoverieswhich were the starting points of the modern sciences of genetics andcytology. The author then proceeds to enumerate in considerable detail andwith numerous examples the various cytological and genetical mechanismswhich have been established up to the present time as playing integral partsin evolutionary change.The book is confident in tone, perhaps too much so, in that the difficultiesyet remaining are almost ignored. One example is the treatment of the originof doqinance, for though the author in his chapter on "Genes and Characters"when considering the genetics of rabbits and of man assumes that dominanceis prevalent in the wild species, no attempt is made to account for this eitheron Fisher's theory of dominance or on any other theory. The possibility of theexistence of further mechanisms and the limitations of existing theory are notdiscussed and it is difficult at times for the reader to distinguish betweenestablished fact and unproved theory.In particular the concept of "genetical species" is open to criticism.Emphasis is rightly laid on the contribution that genetics and cytology canmake to taxonomy, in relation particularly to the species concept: the statementis made that "On this view a species is no longer an arbitrary conceptionconvenient to the systematist, a mere new name or label, but rather a realspecific entity which can be experimentally demonstrated genetically andcytologically." This treatment of a species as a genetical entity divorced fromits environment is as pernicious as the practice of regarding a species as aconvenient herbarium unit equally divorced from its environment.Whether "species" exist would seem to depend primarilyon two things (apart from such species as have arisen through polyploidy andhybridisation): the size of mutations and the time during which mutationshave been taking place in any group. For if it is believed that evolution occursmainly by mutations of a single character and such mutations are takingplace with any considerable frequency in all organisms all the time, the stabilityof species in nature will depend on elimination from among such mutationsand this must in turn depend on environmental conditions and geographicalisolation, in which case the concept of the "genetical species" can have littlerelation to actual fact. If, on the other hand, such mutations occur with considerablefrequency only at considerable intervals of time, and if evolution takesplace during such periods with subsequent stabilisation of species by theenvironment (and on the evidence at present before us, one would judge thisto be the case) then the species is an entity determined in part by inheritable