280 



KNOWLEDGE 



[December 1, 1899. 



class under fennentation the efferrescenco which characterises 

 the action of a mineral acid on a carbonate. But we have moved 

 very far since then. To adequately recapitulate all the changes 

 in the opinions held by chemists and physiologists of the nature 

 of fermentation, and to provide a satisfactory account of modern 

 work on this interesting study, it is necessary, as Prof. Green's 

 book shows, to have a volume of nearly five hundred pages. 

 The aeration of dough and the common production of alcohol 

 were very early correctly associated with fermentation, and 

 towards the end of the sixteenth century putrefaction was seen 

 to have much in common with the other two processes, but it 

 was not recognized till 16511 that they all differed widely from 

 mere effervescence. The deposit observed as an invariable 

 accompaniment of fermentation was first microscopically ex- 

 amined by Leuwenhoek about 1682, but he failed to recognize 

 its vegetable nature — it was not till about 18'25 that Cagniard 

 de Latour made this quite clear. This distinguished observer 

 concluded that the globules he saw under the microscope dis- 

 engaged carbon dioxide and fermented the liquid by some effect 

 of their vegetation. Meyen, later, pronounced the organism a 

 fungus. The more satisfactory views of Pasteur followed, and 

 after much research by many workers, in 1833 Payen and Persoz 

 extracted from germinating barley the now familiar diastase 

 which they distinguished as an " unorganized " ferment. In 

 1845, Mialhe prepared diastase from saliva. In 1836, Schwann 

 demonstrated the existence of pepsin in gastric juice. And so 

 the idea of two classes of ferments was led up to — "organized" 

 ferments and enzymes— that is, unorganized or soluble ferments. 

 Prof. Green traces at some length all these stages in the history 

 of the study of fermentation, and shows that the present definition 

 of the process must be " the decomposition of complex organic 

 material into substances of simpler composition by the agency 

 either of protoplasm itself or of a secretion prepared by it." 

 Though of necessity written in somewhat technical language, 

 the earnest student will find in this well printed volume a clear 

 and interesting account of the chemistry and physiology of most 

 important processes in the economy of the organic kingdom. 



The History of the European Fauna. By R. F. Scharff, B.sr., 

 PH.D. (Walter Scott.) 6s. An example from Dr. Scharff's 

 introductory chapter will indicate the nature of the questions 

 with which he deals in this very readable volume. The 

 Arctic hare " is in the British Isles confined to Ireland and 

 the mountains of Scotland ; and if it were not for the fact that 

 its bones have been discovered in a cave in the south-west of 

 England, we should never have known that, formerly, it must 

 have inhabited that country as well.' Its bones have not been 

 found in Southern Europe, but the nearer we get towards the 

 North Pole the more abundant its remains become. Hence it 

 has probably reached its present habitat from the north. 

 Throughout the book geology and zoological distribution, as we 

 know it to-day, are both utilised in explaining the history of 

 tyjjical European fauna. It is demonstrated that the former 

 distribution of land and water is intimately connected with the 

 origin of the animals under consideration, and these changes are 

 traced by observations on the actual areas occupied at the 

 present time by mammals, snails and earthworms. The larger 

 problem is approached by a preliminary careful consideration 

 of British fauna, then after reviewing the Arctic fauna,- the 

 great migrations known as Siberian, Oriental, and Lusitanianare 

 explained and detailed, and the book concludes with an account 

 of the Alpine fauna. The maps which indicate in a general 

 way the extent of former seas and continents are not intended 

 to be strictly accurate, but admirably serve to illustrate the 

 broad features of the distribution of land and water during the 

 chief geological epochs. Dr. Scharff's book will provide anybody 

 who wishes to learn with a clear and instructive account of the 

 distribution of the various forms of animal life in time — a 

 subject quite as fascinating as the kindred one of their distribu- 

 tion in space. 



The Birds of Breconshire. By E. Cambridge Phillips, F.L.S., 

 M.B.o.u. (Brecon : Edwin Da vies.) Illustrated. Books dealing 

 with the avi-fauna of a county — and now there are many— are 

 always useful and instructive, and the one now before us is no 

 exception to the rule. Mr. Phillips has been a careful recorder 

 of the birds found in his county for many years past. Seventeen 

 years ago he printed for private circulation a list of the birds of 

 Breconshire, of which the present book may be called a revised 

 and enlarged edition. It is very encouraging to learn that since 



the first edition appeared, several birds, and among them some 

 which are becoming rare in this country, have increased in 

 numbers in Breconshire. On the other hand it is deplorable 

 that a fine bird like the red kite, which was once very common in 

 England and Wales, now, in the words of the author, " hardly 

 holds its own in Breconshire," and where is it to be found in 

 England ? The harriers, too, once common, are now nearly 

 extinct in Breconshire. The book is provided with a summary 

 and a sufficient index which becomes a necessity owing to the 

 somewhat strange classification adopted. Residents in the 

 county taking any interest in birds should certainly procure 

 the book, while ornithologists generally will find it a useful 

 and interesting addition to other county avifauna. 



The Wheat Problem.. By Sir William Crookes, F.R.S. (Murray.) 

 Paper, '2s. 6d. ; cloth, 3s. 6d. Sir William Crookes dwelt, in 

 detail, on the wheat problem in his address before the members 

 of the British Association in September, 1898, and the severe 

 criticisms hurled at him since that time have resulted in in- 

 ducing Sir William to issue this book — partly in self-defence, 

 and to some extent as an amplification of the views expressed 

 in his address. " Having pondered disputed points," says Sir 

 William, in the preface, " I cannot in any material degree 

 modify my estimates of the future producing capacity of the 

 wheat fields of the globe. ... If at the end of another genera- 

 tion of wasteful culture my forecast is invalidated by the 

 unforeseen, I cheerfully invite friends and critics to stone me as 

 a false prophet." The first fifty pages contain the original 

 address ; twenty-five pages are occupied with a review of our 

 present and prospective food supply ; about eighty pages set 

 forth replies to various critics. Quite apart from contro- 

 versial matters, however, the book is a useful one to all 

 interested in the production of wheat both from the com- 

 mercial and scientific points of view. Although the author 

 has given us an imposing array of facts, there are also some 

 statements intermingled therewith that will not withstand 

 the criticism of those whose business brings them into 

 close relations with the soil and the markets where produce 

 is distributed. For many years back it has not been 

 worth while to bring new land under cultivation in England, 

 or to farm high in other countries. But let prices rise, make 

 it worth the farmer's while, and, even with present knowledge, 

 the starvation which Sir William so confidently predicts can be 

 kept at bay for long years to come. 



Energy and Heat. By John Roger. (Spon.) Illustrated. 

 2s. This little book, comprising some thirty-six beautifully 

 printed pages, in all the glory of cloth boards, has been on our 

 table for some weeks now. It came to hand at an unfortunate 

 time — a time when we were suffering from too great an intensity 

 of heat, and, in consequence, seemed to be without energy. In 

 the second hne of the introduction we note the expression " so- 

 called latent heat," and our thoughts fly back to a period prior 

 to our own existence ; in fact we remember that Cavendish 

 objected to the use of the term. In the first chapter — 

 " Heat " — we read : " It may, however, be transmitted readily 

 from one body to another, the tendency being to preserve a 

 uniform degree of pressure " ! ! and, later : " Therefore it may be 

 said that heat is elastic, or compressible." One of Davy's very 

 earliest works would set Mr. Roger right on this point. Chapter 

 II. is headed exactly in this way : " Temperature {Pressure)." 

 Now which is which ? We tackle the chapter, hoping to find out. 

 The " Theori/ of the sponge," otherwise known as the Caloristic 

 doctrine among the ancients, continues to hold the floor, with just 

 one improvement — pressure means temperature ! ! In Chapter III. 

 we have " As a thermometer is a measure of the temperature." 

 Now, common sense at once tells us that it is the reading of the 

 thermometer which is this, and Mr. Roger, to be consistent, 

 should have written pressure here for temperature. But that 

 latter error crops up more than once ; we never know whether 

 he has or has not abandoned his convention for the moment. 

 The concluding sentence of this chapter refers to the latent heat 

 of steam, and we find : " The heat, therefore, has not become 

 latent, but has simply been diffused over a larger volume." In 

 other words, the sponge theory is clung to tenaciously. Following 

 on, and, indeed, based on all this a determined effort is made to 

 show that the steam engine is a more efficient apparatus than we 

 usually deem it. Later — page 35 — it is suggested that frictional 

 heat is due to induced electrical currents. Finally, if Mr. Roger 

 is a very young writer, we would suggest his trying again, but 



