348 SCIENCE PROGRESS 



of course, of more general interest. The author points out the probable im- 

 provement which would result to the baking industry from the use of artificial 

 leavens containing, in addition to substances which generate carbon dioxide, some 

 suitable proteolytic enzymes, since it would appear that most of the advantage 

 observed in the use of compressed yeast over ordinary brewer's yeast is due to 

 the more favourable action on the gluten contained in the flour of the proteolytic 

 enzymes in the compressed yeast. 



With regard to brewing, the author holds the view that a more economical 

 and nutritive beer should be obtainable by the use of enzymes cultivated on cheaper 

 materials than barley malt. As an illustration of the improvement resulting from 

 the employment of selected enzymes, the cheese-making industry is cited, in 

 which the efforts of scientific workers have ensured more uniform and certain 

 results. Among other subjects dealt with are the role of proteolytic enzymes 

 in tanning, in the formation of petroleum, in soil bacteriology, in the recovery of 

 nitrogenous waste and in the production of artificial nitrogenous foods, all of which 

 provide most interesting reading and much useful information. 



The least satisfactory parts of the book are the bibliographies, which bear traces 

 of having been only hastily revised, with the result that many names are misspelt 

 and dates and titles of papers are frequently omitted. Apart from these minor 

 defects, however, the book may be confidently recommended as a most valuable 

 compendium of the subject it deals with. 



P. H. 



BOTANY 



Botany of the Living Plant. By F. O. Bower, Sc.D., F.R.S., Regius Professor 

 of Botany in the University of Glasgow. [Pp. x + 580, with 147 figures.] 

 (London : Macmillan & Co., 1919. Price 25.?. net.) 



Several excellent introductory textbooks of botany have appeared in this 

 country in recent years, and also a number of textbooks written for those pre- 

 paring for special examinations. Prof. Bower's book differs from the former in 

 being a full presentation of the fundamentals of botany, while it is free from the 

 disadvantages of a book written for a special examination. It should be of much 

 use to the University student beginning the study of botany, while it is written in 

 such plain and simple language that the non-scientific reader who wishes to 

 become acquainted with the problems of plant life should find here what he wants. 

 The five divisions of the book follow the five main divisions of the plant 

 kingdom, commencing with the Angiosperms and concluding with the Thallophyta. 

 As might be expected, the morphological aspects of the subject are always 

 excellently treated. The treatment of physiological matters, on the other hand, 

 often calls for some criticism. Examples may be cited from two chapters. In 

 the chapter on the Water- Relation the staining of the walls of the tracheides and 

 vessels of the wood by coloured liquids, and the stoppage of the transpiration- 

 stream by plugging with gelatine the cavities of the tracheae of a cut shoot, are 

 advanced as conclusive evidence that the transpiration-stream takes place through 

 the cavities of the vessels. It only shows, of course, that the ascent of water takes 

 place through the vessels and tracheides ; it does not eliminate the possibility of 

 passage through the walls, as it is these latter which are, of course, stained by 

 the dye, while the gelatine used to block the cell cavities may also affect the 

 permeability of the walls. As Dixon has shown, further evidence than this is 

 necessary to establish the location of the conducting channels. 



