482 SCIENCE PROGRESS 



author's views upon the intimate relationship between colloids and crystal- 

 loids in the living organism, and the effect of their mutual interaction upon 

 rhythmic processes such as fatigue and recovery ; the second chapter deals 

 with speculations on the possible origin of life by the gradual evolution 

 upon the cooling globe of inorganic colloidal solutions, which in presence 

 of sunlight were able to effect photosynthesis ; then follows a description 

 of the author's own experiments upon the production of formaldehyde by 

 the action of colloidal ferric hydroxide upon carbon dioxide in sunlight. 

 In the third chapter is to be found an account of experiments by which the 

 author seeks to demonstrate the assimilation of nitrogen from the air by 

 the green plant — experiments which will hardly carry conviction to the 

 critical reader. The remaining chapters are devoted to enzymes and cata- 

 lysts and secretion and glandular mechanism, and the equilibrium of colloid 

 and crystalloid in living cells. While it must be acknowledged that the 

 book, as a whole, contains a number of original and suggestive ideas, one 

 cannot help wondering whether the methods employed for their experi- 

 mental verification are so unimpeachable as to enable them to be recom- 

 mended for the guidance of students of Honours Schools, for whose benefit, 

 according to the Preface, the book is intended. 



P. H. 



Dairy Bacteriology. By Orla- Jensen, Dr. Phil, translated from the 

 second Danish Edition by P. S. Arup, B.Sc, F.I.C. [Pp. xii + i8o, 

 with 70 illustrations.] (London: J. & A. Churchill, 1921. Price 

 1 8s. net.) 



The author, who is professor of technical bio-chemistry in the Polytechnic 

 College of Copenhagen, was formerly Director of the Swiss Experimental 

 Dairy Farm, and has thus an intimate knowledge of the highly-evolved 

 dairy industries of two countries, and the translation of the second Danish 

 Edition now makes his accumulated experience available to English readers. 

 The first fifty pages of the book are devoted to a brief introduction to the 

 general properties and methods of cultivating bacteria and moulds. The 

 second part of the book, which is more specialised and valuable, deals with 

 the cleaning of milk, the normal and abnormal microflora of milk, and the 

 preservation of milk ; then follow chapters on Lactic Acid Fermentation in 

 the Dairy Industry, on the microflora of butter, and on the ripening and 

 defects of cheese ; the final chapter deals with methods of judging of the 

 cleanliness and freshness of milk, and makes a strong appeal, as indeed does 

 the whole book, for the maintenance of a high standard of cleanliness in 

 all stages of the handling of milk from start to finish. It is to be hoped 

 that this translation may be widely read by those interested in the improve- 

 ment of the milk supply of this country, and that it may contribute to the 

 attainment of the sequence — healthy and clean cows, good milk, healthy 

 children — with which the author concludes a very interesting and readable 

 book. P. H. 



Fundamental Principles of Organic Chemistry. By Charles Mouren, 

 Member of the Institute, and of the Academy of Medicine ; Professor 

 at the College de France. Authorised Translation from Sixth French 

 Edition by W. T. K. Braunholtz, B.A., A.I.C. [Pp. xviii + 399.] 

 (London : G. Bell & Sons, Ltd, Price 12s. td. net.) 



In the author's Preface to the English edition he states that, while "there 

 is no dearth of chemical treatises proper, . . . small initiatory books of a simple 

 and at the same time high character are, however, rarer." The present 



