REVIEWS 693 



that occur in the food salts, as the reactions are complex and little is known 

 about them. In spite of much research the true cause of clover sickness is 

 still uncertain, and it is impossible to say definitely that it is caused by bac- 

 teria (p. 84), while finger-and-toe disease in turnips is the result of the attacks 

 of protozoa. Similar inaccuracies prevail in the morphological chapters, as 

 where the hairs of the cotton-grass are said to be the perianth (p. 199), and 

 honesty and spurrey are included among winged fruits (p. 200). The list 

 of criticisms might be extended indefinitely, but it is impossible to do more 

 than select a few instances that indicate the slipshod writing of the whole 

 book. 



Illustrations are numerous, but the absence of index lines often leaves 

 the point of the sketch in doubt {e.g. fig. 23), and in most cases a reproduction 

 of a classical drawing would be more effective than the feeble original ones 

 presented. Some figures fail in their object entirely, as fig. 3, which purports 

 to show the difference between the exogenous origin of branches and the en- 

 dogenous origin of roots, but in fact does not do so, while in fig. 6 careless 

 revision of proofs has passed an indicated reversal of the true positions of 

 xylem and phloem. 



The scheme of the book is sound enough, but the presentation of the 

 subject-matter is so faulty that it is impossible to recommend it for serious 

 perusal. 



W. E. B. 



ZOOLOGY 



An Introduction to General Physiology, with Practical Exercises. By W. M. 



Bayliss, M.A., D.Sc, F.R.S. [Pp. xiv + 238.] (London: Long- 

 mans, Green & Co., 19 19. Price 7s. 6d. net.) 



Professor Bayliss has given us, in his Introduction to General Physiology , 

 a thoroughly delightful and valuable work. 



It comprises the best portions of his well-known Principles of General 

 Physiology, rewritten for the use of beginners in biology, and presents the 

 physical and chemical properties of protoplasm, and of its products, viewed 

 from the standpoint of Energetics. 



One would like more about protoplasm itself, particularly in diagram. 

 A visual image of its substance, though necessarily incomplete and inaccurate, 

 would be helpful as well as encouraging to the beginner. More readily in- 

 telligible might be the terms " available " and " not available " in place of 

 " free " and " bound," on pp. 12 and 13. Not quite clear is the account of the 

 anions on p. 59. Could, for example, OH', or even HCO'3, replace much of 

 the CI' without harm ? Of great interest, on p. 85, would be an account of 

 expired air as the product of diffusion, due to differences in tension, between 

 inspired air and the air of the pulmonary alveoli. On such points as these, 

 perhaps, opinions may differ. 



There will, however, be no difference of opinion that the book is a perfect 

 God-send to the student of biology. It gives him, between one pair of covers, 

 selected for him and explained in its bearings on structure and on function, 

 an immense fund of valuable information which he had, formerly, to seek in 

 many books, to disentangle from irrelevance to his needs, and to interpret 

 in relation to biology as best he was able. 



To the teacher, also, its value is considerable. To him — the preface, the 

 frequent references to the author's " Principles," and the details of his class 

 work will be of especial interest and assistance. 



The difficulties in compiling a book on such novel lines are, obviously, 

 both numerous and great. Prof. Bayliss has recognised this, and, thanks to 

 his foresight, has, in overcoming them, achieved a really conspicuous success. 



W. L. S. 



4S 



