452 SOME NEW BOOKS [december 



power of reproducing vegetatively. Almost any portion of the plant will, under 

 favourable conditions of moisture and temperature, give rise to a new individual, 

 and there are also a great variety of means by which this can be naturally 

 effected. It is this last aspect of their biology which forms the subject of Dr. 

 Correns' substantial contribution to Muscology, a work which we are sure will 

 be perused with much interest by the increasing number of botanists who are 

 specially interested in the Mosses. The book, which is partly special, partly 

 general, opens with a short introduction (pp. xvii.-xxiv.), in which terms are 

 explained and methods described. The " brood-organs " are in brief those 

 organs which are definitely produced for the purpose of vegetative reproduction ; 

 the " Stecklinge," on the other hand, are those parts of the plant which will on 

 separation form a new individual, but have not been definitely developed to 

 that end. The greater part of the book (pp. 1-322) is " special," comprising 

 first an account of the investigated cases of multiplication by "brood-organs," 

 arranged systematically in tribes, families and genera, and secondly those 

 species in which the other method obtains. This is followed by a "general" 

 part (pp. 325-360), arranged in five sections, treating of the morphology and 

 phylogeny, structure, development and germination, more especially of the 

 " brood-organs," and of their value for systematic purposes. A bibliography 

 occupies a few pages, and the book closes with an index of the plants mentioned 

 in the text. One cannot have too many illustrations in a work of this kind, 

 and the 187 which are distributed through the text form a valuable help to 

 the elucidation of the subject-matter. R. 



ANOTHER BOOK ON BACTERIA. 



Bacteria, especially as they are related to the Economy of Nature, to 

 Industrial Processes, and to the Public Health. By Geokge Newman, 

 M.D., F.R.S.E., D.P.H. (Camb.), etc., Demonstrator of Bacteriology 

 to King's College, London. Pp. viii. + 351, with 15 micro-photo- 

 graphs by E. G. Spitta. London: John Murray, 1899. Price 6s. 



In his short preface the author expressly disclaims any attempt to write 

 either a record of original work or a laboratory text-book. His object is merely 

 to discuss in a popular scientific form the present state of knowledge concerning 

 bacteria. As the title indicates, the bacteria considered are not only those 

 capable of producing pathogenic effects, but include the vast number of those 

 which are concerned in natural and industrial processes. 



Embracing so wide a range of subject, and being designedly written to 

 suit the lay reader, the descriptions are unavoidably often sketchy and in- 

 complete. But the author is in his happiest vein when dealing with the 

 role of bacteria in natural processes, and with their industrial application, and 

 to this the greater part of the book is devoted. The chapters on the bacteria 

 in the soil, the bacteria of fermentation, and the bacteria of milk and its 

 products, are specially valuable to medical readers for the lucid and interesting- 

 account they give of the far-reaching beneficial effects of bacteria. The 

 ordinary student of medicine is too apt to associate bacteria with disease alone, 

 and the author is to be congratulated on presenting in so attractive a form an 

 outline of the immensely greater activities which these lower vegetable organisms 

 possess. Whether the brief description of the chief pathogenic bacteria could 

 be of equal value or interest to the lay reader, we are inclined to doubt, and 

 it would be easy to criticise adversely some of the details given in this section. 

 But the shortcomings of this latter part are only of minor importance, and 

 do not detract from the value of the preceding chapters. 



The book is illustrated by several good illustrations from micro-photographs, 

 and by a number of outline drawings of bacteria, for which the writer claims 

 only a diagrammatic significance. It may be permitted to point out that some 



