556 



NATURE 



{Oct. 14, 1880 



was emphatically wanted was a history and discussion of 

 details to give shape and fulness to the more meagre 

 accounts found elsewhere. Doubtless many will say that 

 the work contains a great deal more than can possibly be 

 wanted by the student of medicine or even of physiology. 

 We will not presume to answer the difficult question, 

 How little physiology a medical student may know with- 

 out his educational status being considered " mean " ; but 

 this we may say, that there is not a page in this work, the 

 study of which will not prove profitable not only to the 

 medical student, but even to the medical practitioner. 



We trust that the author will as soon as possible be 

 able to complete a work of which the first part will 

 increase his already high reputation, and certainly must 

 be regarded as a most noteworthy addition to English 

 physiological literature. M. Foster 



PEAT-MOSSES 

 The SphagnaiccE or Peat-Mosses of Europe and North 

 America. By R. Braithwaite, M.D., F.L.S. (London : 

 David Bogue, 1880.) 



THE peat-mosses are a peculiarly interesting group of 

 cryptogamic plants, which has attracted the atten- 

 tion of even ordinary observers from a very early period. 

 No group of plants is more clearly defined in structure, 

 in family likeness, and by the localities in which they are 

 found. The wanderer over our moorlands, tlie sportsman 

 in pursuit of game, are as familiar as is the botanist with 

 their dense green or ruddy-coloured tufts, now covering over 

 some damp spot or filling up some bog hole with a vast 

 mass of vigorous vegetation. Nor is there wanting to them 

 an economic value, and that of too great an importance to 

 be overlooked by even the most careless, for it is past gene- 

 rations of these bog-mosses which form the vast deposits 

 of peat, for which as an article of fuel no substitute is in 

 many parts of Europe attainable. The name sphagnus 

 was first used, by writers like Theophrastus and PHny, to 

 indicate some of the spongy lichens, but was restricted 

 to a genus of mosses by Dillenius more than a century 

 and a half ago, " which were like none of the terrestrial 

 mosses, but were produced always in bogs and marshes." 

 Dr. Braithwaite, in the volume before us, gives a most 

 excellent sketch of the literature of the genus, tracing it 

 from Dillenius, Linneus, Hedwig, to Miiller, Wilson. 

 Sullivant, Schimper, Lindberg, and others. For a long time 

 Prof. Schimper' s work was the best on the subject, and 

 Dr. Braithwaite mentions it as very complete in its details 

 of structure, both descriptive and pictorial, and as leaving 

 hardly anything to be desired. Of works more especially 

 relating to the development and minute anatomy of the 

 group, allusion is made to the important memoirs of von 

 Mohl, Carl Nageli, Dozy, Hofmeister, Russow, Pir^, and 

 Rozd. He then proceeds in a second chapter to some 

 general observations on collecting, preparing, and on the 

 points to be observed in the determination of a species. 



In a third chapter the vegetative system of the group 

 is discussed. To our mind this chapter might well have 

 been extended. The details given of the germination of 

 the spores are too few, nor is the following chapter on the 

 reproductive system free from the same defect ; and as 

 to the illustration of these two chapters, it will suffice to 

 mention that it is confined to a single plate. As the 



charming plates illustrating the descriptive portion of the 

 work are, we trust, likely to serve for more than one 

 edition of it, we would suggest that, in the event of a 

 second edition, some half-dozen supplementary plates 

 might be given, on which would be represented the 

 embryology of the group. 



Between fifty and sixty species of Sphagnum are known, 

 of which about one-third are tropical. They are most 

 abundant in the north and south temperate zones, in the 

 higher latitudes of which they often cover over a large 

 expanse of surface. Dr. Braithwaite describes twenty 

 species as found in Europe and North America, that is 

 about one-third of all the known species. Of the others, 

 seven species are described as from Brazil, seven from 

 Central America, four from Guadaloupe, seven from 

 .^ustralia and New Zealand, four from the Eastern 

 Archipelago, two of these, S. sericeum, C. Miill., and 

 S. Holleanum, Dozy and Molk, known only in a barren 

 state, but remarkable for having the stem leaves precisely 

 like the branch leaves in form and structure, their hyaline 

 cells being without fibres, but with a single apical pore. 

 The only species from tropical Africa is S. Africantim, 

 Duby. 



Dr. Braithwaite points out that the range of variability 

 in the species is in this group most extensive, so that in 

 their determination one must rely on minute anatomical 

 distinction for their essential characters, as in many cases 

 size, colour, direction of leaves, habit, presence or absence 

 of fibres in the hyaline cells of the stem leaves, will all 

 alike fail. In the separation of the Sphagnina as a sub- 

 class from the Bryinae or frondose mosses. Dr. Braith- 

 waite follows the earlier views of the illustrious Schimper. 

 He groups the species described in nearly the same 

 manner as Lindberg, adopting his three sections— 

 Eusphagnum, Hemitheca, and Isocladus. The Euro- 

 pean species are all located in the first section. The 

 descriptive details are very clearly given. The synonymic 

 lists are evidently made out with great care, and the 

 varieties which in many of the species are, as is well 

 known, veiy marked, are not only described, but in several 

 cases figured. The twenty-eight beautiful coloured plates 

 illustrating the species and varieties are all from draw- 

 ings by the author, and they contain complete anatomical 

 details of the stem and leaf structures. The work is 

 brought out in a style worthy of the subject, and we trust 

 will find its way not only into the hands of the botanist, 

 but, as it well deserves to do, into the possession of all 

 who take an intelligent pleasure in studying our native 

 mosses. 



OUR BOOK SHELF 



Vox Populi: a Sequel to the "Philosophy of Voiee." By 



Charles Lunn. (London : W. Reeves, 1880.) 

 We are told in the preface that " the present work is a 

 reprint of articles that appeared in the Orehestra," and 

 that "now it has been discovered Galen (a.d. 180), 'the 

 father of physicians,' as he is called, advanced the same 

 physical views as those for which I (Mr. Lunn) have con- 

 tended, my controversial work is ended :— it is scarce 

 worth while to re-write." Was it then worth while to 

 re-print ? In the introduction the author tells us that his 

 articles were written " to clear up some ambiguous points 

 in my (Mr. Lunn's) 'Philosophy of Voice,'" and that 

 "this without the former work is incomplete, as that 



