REVIEWS 791 



still the sheet anchor of those who investigate the phenomenon of irritability, but 

 fresh light is shed upon the problem by employing other kinds of excitable proto- 

 plasm such as are found in the protozoa. Prof. Verworn emphasises the 

 importance of this branch of work in the book just published. 



His first chapter deals with the history of the subject from the days of Francis 

 Glisson onward, and his second with the general principles of scientific research, 

 especially in relation to the conception of the word cause. It is not until we reach 

 Chapter III. that the author really launches out into his subject proper, and in 

 this and succeeding lectures deals in turn with the varieties of stimuli and the 

 manner of response. We have, for instance, a discussion of the Weber-Fechner 

 law which mainly operates in sensory phenomena, and the "all or nothing" law 

 which he regards as the rule in motor responses. It is pointed out that stimulation 

 as a rule leads to katabolic effects, the intakes of food being practically the only 

 stimulus which leads to anabolism. The processes of induction are of necessity 

 included with those of irritability. The importance of a due supply of oxygen is 

 largely dwelt upon, for it is^upon an interference with this that the phenomena of 

 " refractory period " and of fatigue depend. The concluding chapters deal with 

 the " interference " of stimuli, and with inhibition which is largely due to 

 interference, and with the very important question of depression of irritability as 

 especially illustrated during narcosis. 



Such a hasty summary of the main contents 01 the book is sufficient to 

 illustrate the important nature of the themes it treats of, and one hopes it will 

 be sufficient to induce those interested in physiological advance to purchase it. It 

 is, however, only right to warn intending purchasers that they are not to expect 

 light and easy reading. It is not suited to beginners, for it presupposes a ground- 

 work of physiological knowledge. To the advanced student or professed 

 physiologist, especially if he is a rapid thinker, some of the sections, moreover, may 

 prove rather " irritating," for they labour points which are pretty obvious. 



The translation has been admirably carried out by Frau Verworn, and in a book 

 published in the United States one naturally forgives such Americanisms as center 

 and acetat. But the words functionation, oxyclable, and excitate do not strike 

 one as happy ; they are not English and one doubts whether they are even 

 American. 



W. D. H. 



Applied Mechanics for Engineers. By J. Duncan, Wh.Ex., M.I.Mech.E. 

 [Pp. xv + 718.] (London : Macmillan & Co., 1913. Price 8.r. 6d. net.) 



This book deals in two parts with Materials and Structures, and Machines and 

 Hydraulics. There is, of course, no logical reason for not dealing with heat 

 engines and other branches of engineering, when treating with mechanics for 

 engineers. But no one can complain that enough has not been crowded into the 

 seven hundred odd pages as it is. It may be said at once that the book will be 

 found very useful for students who have been properly taught, and who wish to 

 possess in a concise form a summary of the material dealt with in the usual 

 engineering examinations. They will be further helped by the numerous examples, 

 particularly as answers to these questions are given at the end of the book. All 

 that can be done by a good compiler and an excellent printer has been achieved. 

 The formulae and tables are admirably clear, and the illustrations throughout are 

 excellent and carefully drawn. The student will find that the numerous proofs of 

 different formulas are stated in a concise form, and the cross references are con- 

 veniently given. It is quite necessary for a student to understand that he cannot 



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