September 4, 1914] 



SCIENCE 



351 



X-Rays. An Introduction to the Study of 

 Eontgen Rays. By G. W. 0. Kaye. Long- 

 mans, Green & Co. 



Since 1895, when Eontgen made his epoch- 

 making discovery of the X-rays, an immense 

 amount of research work, experimental and 

 theoretical, has been done on their properties. 

 This work has produced a remarkable series of 

 discoveries of high interest and fundamental 

 importance. A connected account of the 

 latest results in this branch of physics by one 

 who has made several important contributions 

 to it can not fail to be welcome. Dr. Kaye 

 has succeeded in producing a very useful sum- 

 mary of the latest results together with a brief 

 account of the historical development of the 

 subject and numerous practical details which 

 should be useful to any one working with X- 

 rays. The book contains a number of excel- 

 lent illustrations. 



A few minor errors have crept in; for ex- 

 ample, on page 148 it is stated that the total 

 ionization produced by a beam of homogene- 

 ous corpuscular rays is independent of the 

 velocity of the corpuscles, which is obviously 

 absurd. 



Chapter XII. contains a clear account of 

 the recent work, initiated by Lane, on the dif- 

 fraction and reflection of X-rays by crystals, 

 which has established the theory that X-rays 

 are merely light rays of very short wave 

 length. 



Chapter XIII. contains a discussion of the 

 various theories of X-rays which have been 

 put forward. The problem which remains to 

 be solved is the emission of high velocity elec- 

 trons by m.atter when exposed to X-rays. 

 H. A. Wilson 



Irritability, a Physiological Analysis of the 

 General Effect of Stimuli in Living Sub- 

 stance. By Max Verworn, M.D., Ph.D. 

 New Haven, Tale University Press, 1913. 

 To the physiologist who wishes, for the clear- 

 ing of his vision, to return from time to time 

 to a consideration of the fundamentals of his 

 science, no better opportunity can be offered 

 than that contained in the published volume 

 of lectures on irritability by Professor Max 



Verworn. The biologist, too, will find in its 

 pages an unusually rich presentation of the 

 facts of cell behavior, interwoven, correlated 

 and interpreted, with meanings that separately 

 they fail to convey. 



The book, a re-writing of the Silliman Lec- 

 tures of 1911, is a philosophical treatment of 

 the nature of irritability as one of the general 

 manifestations of living material, followed by 

 a study of the laws and effects of stimulation, 

 undertaken for the light that such knowledge 

 may throw on the nature of the vital processes 

 of which irritability is a manifestation. Its 

 facts are drawn from the results obtained dur- 

 ing twenty years consistently devoted to the 

 problem by Verworn and his pupils, and from 

 the work of others in the same field. The im- 

 portance of its conclusions may be estimated 

 from the breadth of its experimental founda- 

 tions. 



The opening chapter gives a careful review 

 of the historical development of our modern 

 ideas of the subject, from the first generaliza- 

 tions of Glisson, with whom originated the 

 " doctrine of irritability," down to Virchow's 

 conclusion that nutritive, functional and for- 

 mative reactions of cells are the basis alike of 

 normal and pathological manifestations in ceU. 

 activity. The importance of Virchow's teach- 

 ings in the modern interpretation of diseased 

 conditions has perhaps overshadowed thefr 

 equally great importance to general physiol- 

 ogy: indeed, these, with inhibition (Weber) 

 and narcosis (Claude Bernard), may be looked 

 upon as the starting-point of Verworn's phi- 

 losophy. 



The second lecture, on the nature of stimu- 

 lation, is perhaps the most striking, containing 

 as it does clearer definitions of the meaning of 

 the words stimulation and irritability than we 

 have had heretofore, and leading to a better 

 understanding of the scope of the unsolved 

 problem of the nature of the vital processes. 

 Beginning with a lucid presentation of the 

 difficulty in differentiating between the 

 " cause," so-called, and the " conditions " of a 

 biological, or indeed of any, process, it is 

 pointed out that " all conditions for a state or 

 process are of equal value for its existence, for 



