July 15, 1909] 



NATURE 



unknown to most students of building- materials, it 

 inifjht be advisable to substitute the more familiar 

 *' mirror." 



However, in spite of a few minor points like these, 

 the book as a whole is well written, and admirably 

 adapted to the class for whom it is intended. It 

 deserves to take a permanent place among the text- 

 books upon the subject, and in future editions the 

 points referred to will no doubt receive attention. 



II. B. 



ECONOMIC BACTERIOLOGY. 



Bacteria in Relation to Country Life. By Dr. Jacob 

 G. Lipmann. Pp. xx + 486. (New York: The JSIac- 

 millan Co.; London: Macmillan and Co., Ltd., 

 1908.) Price 6s. 6d. net. 



Al^RITTEX in non-technical language, this book 

 • »' gives a good account of the activities of micro- 

 organisms. It may therefore be recommended to all 

 those who desire to obtain a general knowledge of the 

 functions of bacteria and the important role they play 

 in relation to daily life, while the intelligent agricul- 

 turist will find a large amount of information which 

 should aid him in his work. After a brief survey of 

 the form, structure, food requirements, and conditions 

 of growth of bacteria, successive chapters deal with 

 these organisms as met with in air, water, and sewage. 

 The relation of water to health and disease is discussed, 

 and the chief factors in connection with the con- 

 tamination and purification of water are detailed. .\ 

 readable account is given of the disposal of sewage 

 and of bacterial systems of sewage disposal. Next 

 follow the most important sections of the book, viz. 

 the relation of bacteria to soil fertility and the influence 

 of manures. We here find accounts of the sources of 

 nitrogen in the soil, of nitrification and denitrification, 

 of the action of leguminous crops in fixing nitrogen, 

 and of soil inoculation with pure cultures of nitrogen- 

 fixing organisms. The proper methods of storing 

 farmyard manure are dealt with at some length, and 

 it is shown that under different conditions of storage 

 the losses of organic matter from the manure stack in 

 three or four months may range from 15 to 20 per cent, 

 to 40 to 50 per cent, of the initial quantity, and valuable 

 suggestions are made on the best means of conserva- 

 tion of manurial constituents, both by proper methods 

 of storage and by the use of chemical fixatives. 



The chapters which follow on milk, its production 

 and preservation, are also excellent. Details are given 

 which show that careful hand-milking yields a better 

 milk as regards bacterial contamination than any milk- 

 ing machine, unless extreme precautions are taken in 

 the sterilisation of the latter. The subject of pasteur- 

 isation of mflk is also critically discussed, and the 

 following extract sums up the author's views on the 

 advantages and disadvantages of the process, views 

 with which we fully agree and which should be widely 

 known : — 



" Pasteurisation is effective for the destruction of 



disease bacteria in milk and for the improvement of 



its keeping quality. It is agreed that city children fed 



on pasteurised milk, properly heated and properly 



NO. 2072, \or,. 81] 



cooled, are less subject to intestinal disturbances than 

 children fed on raw milk. .'\t the same time, it must 

 be admitted that the pasteurisation of milk already 

 filled with bacteria, and the products of their acitivities, 

 will not remedv its defects. The undesirable sub- 

 stances formed bv the bacteria are not entirely 

 destroyed by the heating, and may still cause injury 

 to the person consuming the milk. 



" By resorting to pasteurisation, a dealer may be 

 able to dispose of milk that would otherwise quickly 

 become unsaleable. Similarly, the failure to cool the 

 pasteurised milk quickly and to keep it at a tempera- 

 ture of 50°, or below that, may lead to the rapid multi- 

 plication in the milk of germs producing injurious or 

 poisonous substances. Hence, pasteurised milk should 

 be consumed within twelve hours, or should be imme- 

 diately cooled down to between 45° and 50°." 



The subject of tuberculosis in relation to milk is 

 fully discussed. It is pointed out that large numbers 

 of tubercle bacilli may pass into the excreta of tuber- 

 culous cows, a fact which was fully confirmed by the 

 experiments of our Royal Commission on Tuberculosis 

 as contained in the last report, and it is concluded that 



" Whatever difference of opinion there may prevail 

 as to the extent of human tuberculosis caused by the 

 consumption of milk and milk products, it is conceded 

 bv sanitarians that persistent efforts should be made 

 to eradicate bovine tuberculosis." 



Subsequent chapters deal with milk beverages, 

 butter and cheese, canning, ensilage and fermented 

 liquors. 



The book is adequately illustrated and clearly 

 printed. R. T. Hewlett. 



FORESTRY. 

 (i) Our Forest.^ and Woodlands. By Dr. J. Nisbet. 



New and revised edition. Pp. xxiii + 348. (London : 



J. M. Dent and Co., 1909.) Price 3s. 6d. net. 

 (2) Trees: A Handbook of Forest-Botany for the 



Woodlands and the Laboratory. By the late H. 



Marshall Ward. Vol. v.. Form and Habit. Pp. 



xi + 308. (Cambridge: University Press, 1909.) 



Price 4s. 6d. net. 

 (i) "T^HE first edition of Dr. Nisbet's well-known 

 J- book, "Our Forests and Woodlands," 

 appeared in 1902. The second edition has now been 

 issued, and will doubtless be welcomed by a large 

 circle of readers, not only on account of the interest- 

 ing and important information it contains, but the 

 price is such as to bring it within the reach of many 

 who cannot afford the more expensive, though e.xcel- 

 lent, works on forestry at present available to the 

 English reader. .\ very important, and probably the 

 most outstanding feature of the new edition is the 

 preface, in which the author has given a resmni of 

 the progress which has been made in forestry since 

 the appearance of the first edition. The doings of the 

 various Governmental committees and commissions 

 which have sat of late years are clearly set forth. 

 There is also given a very striking table in the form 

 of an abstract from the " .Annual Statement of the 

 Timber Trade of the LInited Kingdom " for 1906 and 

 1907. Here it is shown that the gross total imports 

 of wood and timber, wood-pulp, and manufactured 

 wood-pulp come to about 37,500,000/. To supply these 



