NA rURE 



425 



THURSDAY, AUGUST 31, 1905. 



BRITISH MOSSES. 

 The Brilislt Moss-Flora. By R. Braithwaite, M.D., 

 F.L.S., &c. Pp. X + 315; 268; 274+ plates. 

 (London: L. Reeve and Co., 1887 to igoS-) 



WE offer to Dr. Braithwaite our most sincere 

 congratulations on tlic completion of this 

 work on his favourite class of plants. Begun, as 

 regards publication, in 1880, it reached completion 

 by the issue of the last part with index and supple- 

 ment in May of this year, so that the course of 

 publication has occupied a space of some quarter of 

 a century. In the last number Dr. Braithwaite takes 

 leave of his readers in a postscript in which he ex- 

 presses his regret that he is unable to include the 

 Sphagnaceae in the work; but he finds that to study 

 these again at the age of eighty-one, and to draw 

 some twenty-five plates, would be hopeless. All 

 lovers of mosses will share in this regret, at the 

 same time remembering that they owe to Dr. Braith- 

 waite an interesting monograph on the peat mosses 

 of Europe and America, published in 1880. The 

 author concludes the whole matter with a quotation 

 of some lines (little known, we suspect) by Ehrhart, 

 which are interesting as disclosing the mental atti- 

 tude of the venerable author at the conclusion of 

 his labours ; they begin thus ; — 



" Vernimm's und siehe die Wunder der Werke, 

 Die, die Natur dir aufgestellt ! 

 Verkiindigt Weisheit und Ordnung und Starke 

 Dir nicht den Herren, den Herren der Welt? " 

 The three volumes of Dr. Braithwaite 's book are 

 illustrated by 128 pages of plates, giving figures of 

 every moss described, with enlarged designs of parts 

 of the various species. Every one of these plates 

 has been engraved from the drawings of the author 

 himself, and together constitute a remarkable monu- 

 ment of his skill and industry. Indeed, the illus- 

 trations may be regarded as perhaps the most dis- 

 tinctive feature of the worlc. In some cases a whole 

 page is devoted to a single species, as Schistostega, 

 or to two species, as in the strange genus Bux- 

 baumia ; but generally four or more plants are dealt 

 with in a single plate. So far as we have compared 

 the figures of our author with nature, we have found 

 his drawings accurate, and the magnified parts very 

 valuable for the purposes of identification. 



If we were inclined to be adversely critical on the 

 plates, we should say that to some extent strength 

 has been sacrificed to elegance. If you turn from 

 the drawings of Braithwaite to the plates of old 

 Dillenius, you are conscious of a marked difference 

 of treatment ; the old figures are more robust and 

 graphic, and the general facies of the plant is 

 more forcibly impressed upon the mind. But this 

 difference is perhaps an inevitable result of our 

 advanced knowledge of the distinctions between 

 kindred species ; the earlier artist was not haunted 

 by the perception of minute details which make the 

 later artist at once more timorous and exact. 



The classification principally adopted by Dr. Braith- 

 NO. 1870, VOL. 72] 



waite is that of Prof. Lindberg, by which the cleisto- 

 carpous mosses are no longer treated as a group by 

 themselves, but are introduced into the stegocarpous 

 families, and are regarded as imperfectly developed 

 forms of more highly organised stegocarpous con- 

 geners. There can be no doubt that the distinctions 

 based upon the presence or absence of a peristome 

 and on the number of teeth in the peristome 

 received an exaggerated amount of attention from 

 many bryologists ; they were for the moss flora some- 

 what as the number of stamens and pistils was in 

 the hands of Linnaeus for phaenogamous plants. 



Whenever a genus contains more than one species, 

 Dr. Braithwaite gives a clavis to the species, 

 arranged dichotomously, and this appears to us to 

 be very carefully and well done— a fact which in- 

 creases our regret that the author has not given 

 similar guidance between the families, subfamilies, 

 and genera of the whole group, so that the student 

 might have been conducted by the use of the 

 necessary differentiae from the summum genus to the 

 ultima species. But where so much has been given, 

 it would be ungracious to complain that something is 

 still wanting. 



Mr. Dixon, in his preface to his " Student's Hand- 

 book of British Mosses " (1896), referred to the 

 book now under review as " Braithwaite 's splendid 

 and elaborate work . . . which has done so much 

 to stimulate the study of these plants in our country 

 and which will doubtless remain our standard work 

 for many years to come." In this generous appreci- 

 ation by one botanist of the work of another, we 

 cordially agree, and we rejoice for ourselves, as well 

 as for the author, at the completion of a noble piece 

 of honest work. 



Before we part from the book we wish to make 

 this review the vehicle of a thought that has fre- 

 quently occurred to us 



In the last number of Dr. Braithwaite 's book we 

 find a notice of Catharinia tenella — which has been 

 found near Goudhurst, in Kent, by that keen 

 bryologist Lord Justice Stirling — mixed with 

 Catharinia angustata. This is only one instance of 

 a common fact, viz. the coexistence side by side of 

 two kindred species. 



Thus, turning over at random some pages of 

 Wilson's " Bryologia Britannica " (a book more easy 

 to use for such a purpose than the luxurious pages 

 of Braithwaite), we find that Fissidens viriditlus is re- 

 corded as growing with F. exilis, Hypnum Swartzii 

 as growing with H. praclongum, Hypnnni chryso- 

 phyllum as found with H. stcllatiim, Hypnum 

 resupinatum in like manner with H. cupressiforme, 

 and Hypnum elegans as often growing with H. 

 denticulatum ; and in all these cases the two species 

 are so nearly akin that they stand next to one 

 another on Wilson's pages. A further search would, 

 we feel sure, bring to light many similar cases, in- 

 cluding those in which forms recognised only as 

 varieties are found side by side with the normal form. 

 This fact seems to us to be worthy of further atten- 

 tion. Is it due solely to the suitability of the same 

 spot to several species of the same genus, or is it 



