March 15, 1906] 



NA TURE 



461 



first part concludes with certain considerations as to 

 the influence of radiations on the equilibrium of living" 

 substances. 



In the second division of the work the author pro- 

 ceeds to render more precise the language prepared 

 in the first part of his study. He reviews the more 

 important types of infection, and particularly con- 

 siders intracellular parasitism and symbiosis; then 

 he passes on to the phagocytic studies of M. Metchni- 

 koff, and uses a language different from the vitalistic 

 expressions of the great Russian savant. Next 

 comes the considerations of the comportment of the 

 living organism towards injections of dead colloids, 

 thus leading up to the study of infection proper, i.e. 

 disease due to living micro-organisms. The above 

 abstracts will suffice to show the aim of the author's 

 book, and chiefly he desires to use " the language of 

 equilibrium," language borrowed from physical chem- 

 istry. He holds the law of Le Chatelier valid for 

 the modification which an organism undergoes when 

 it triumphs over infection. " The modification pro- 

 duced in a system of bodies in a state of equilibrium 

 l>\ a variation of one of the factors in the equilibrium 

 is of such a nature that it tends to oppose itself to 

 ilu variation that determines it." His position is 

 even more clearly defined on p. 184, where he says 

 that he wishes to show that if the immunities that 

 result from the resistance of organisms to infection 

 resemble the phenomena of physical chemistry, the 

 resemblance is exclusively on the physical side. He 

 finds that questions on immunity and serotherapy are 

 discussed in the language of chemistry, even by those 

 investigators who do not accept the theories of 

 Ehrlich — therefore the very words used are filled with 

 unjustifiable hypotheses, and give an inflexible inter- 

 pretation to phenomena. For example, the partisans 

 of the chemical theory of serums admit the existence 

 of two definite and complementary substances, 

 " cytase " and "fixative," the former thermolabile, 

 the latter thermostable, and these thermic relations, 

 according to M. le Dantec, suggest that these sub- 

 stances—even if chemically definite bodies — act in 

 virtue of their physical character rather than in 

 accordance w'ith their chemical structure. 



The phenomena of bacteriolysis receive at the 

 hands of Ehrlich a purely chemical interpretation ; 

 M. le Dantec deliberately states that the chief fault 

 in Ehrlich's theory is that the serum-producing 

 animal must have an immediate and profound know- 

 ledge of chemistry. This can scarcely be seriously 

 meant. 



Nowhere does he give a complete account of the 

 views on immunity and toxins held by Ehrlich, nor 

 is this to be looked upon as a fault, inasmuch as those 

 of Ehrlich's opinions that he does consider he re- 

 gards as entirely untenable. Still, this omission (if 

 Mich it be) shows that the book will be of little use 

 to a student really needing an introduction In general 

 pathology, however interesting and instructive the 

 work may be to the thoroughly equipped investigator; 

 and to the latter the learned author doubtless 

 addresses himself. First and foremost he is a bio- 

 logist, and, moreover, is imbued with the belief that 

 NO. 1898, VOL. 73] 



pathology is capable oi throwing a Hood of light on 

 biological questions. 



Main pages <>l the work remind us of the author's 

 well known papers in the Annals of the Pasteur 

 Institute, and these pages will be read by many with 

 reminiscent pleasure. 



Nowhere is the author more interesting and lucid 

 than in his discussion of Mendelian or discontinuous 

 heredity; his quotations are apt and instructive; his 

 own remarks carry with them the imprint of careful 

 study and original thought. In this connection he 

 replaces the " representative partieles " of Darwin 

 and Weismann by the Pasteurian word " microbe "- 

 meaning thereby particles productive of diatheses — 

 and claims that by so doing he loses nothing in the 

 narration of the facts, while gaining the advantage 

 of placing the diatheses (characters of Mendelian 

 heredity) apart from the characters of heredity 

 properly so-called. 



The book is well worth careful reading, and the 

 author is to be congratulated on a work which will 

 challenge the attention of the more advanced students 

 of pathology. Wm, St. C. Symmers. 



OUR BOOK SHELF. 

 Die optischen lnstrumente. By Dr. Moritz von Rohr. 



Pp. v+130. (Leipzig: B. G. Teubner, 1906.) 

 The aim of this little book, one of a series dealing 

 popularly with various subjects of scientific or general 

 interest, is to give a simple account of the develop- 

 ment and modern theory of optical instruments, and 

 to make clear to readers possessing no special 

 technical knowledge the main features of their optical 

 construction. The treatment is largely based on the 

 work of Abbe ; and in the introductory chapters, which 

 deal with the general principles governing the form- 

 ation of optical images and the consequences de- 

 pendent on the characteristics of the eye, special 

 attention is given to the question of aperture and the 

 limits of the image-forming pencils, and to the 

 manner in which the perspective of a picture may be 

 modified in the image. In the application of these 

 considerations to the photographic lens, the micro- 

 scope, and the telescope, there is some novelty and 

 interest. In other respects a clear and concise account 

 is given of the main properties and aberrations of the 

 different instruments, whether for objective or sub- 

 jective use, with some brief historical notes. The 

 section on the photographic lens is followed by useful 

 particulars as to enlarging and projection apparatus ; 

 the description of the microscope includes a short 

 explanation of Abbe's theory of microscopic vision, 

 of the relation of " numerical aperture " to resolving 

 power, and of the sine law, and even admits of refer- 

 ence to the possibilities of photomicrography with 

 ultra-violet light. To the description of the ordinary 

 forms of telescope are added some notes on the prism 

 binocular as constructed by the Zeiss firm. The 

 diagrams and illustrations are noticeably well drawn 

 and clearly printed. 



Second Year Chemistry, a Handbook for Laboratory 

 and Class Work. By Prof. Edward Hart. Pp. 

 vi+165. (Easton, Pa.: The Chemical Publishing 

 Co., 1905.) Price 1.25 dollars. 

 The plan of this book is to begin, after a few theo- 

 retical generalities, with some careful quantitative 

 determinations. Thereupon follow qualitative ana- 

 lysis, chemical arithmetic, and, finally, more quanti- 



