REVIEWS 515 



on physics and those on chemistry usually deal with it in a perfunctory manner. 

 Cooke's Nciu Chemist}')'^ in the International Science Series — now a book of some 

 antiquity— is almost the only work that does justice to the subject. Now there 

 can be no excuse for the neglect of Avagadro's theorem and every self-respecting 

 student of molecular theory should take pleasure in mastering Cannizzaro's essay, 

 on account of the subject-matter and also because it is so brilliant an example of 

 pedagogic method. 



The letter is full of noteworthy paragraphs to which attention might well be 

 specially directed : none is more important than the following : — 



" In order to lead my students to the conviction which I have reached myself, 

 I wish to place them on the same path as that by which I have arrived at it — the 

 path, that is, of the historical examination of chemical theories." 



And it may be added, of chemical discoveries ; indeed, if students of chemistry 

 regularly followed the path indicated by Cannizzaro, they would have some chance 

 of acquiring feeling as chemists ; a careful study of his memoir should lead many 

 to appreciate the value of logical statement and to regret the frequency of its 

 absence from modern writings. 



Die Pflanzenproteine. Von Thomas B. Osborne, New Haven, Conn., U.S.A., 

 Deutsche tJbertragung von Frau Helene Schlesinger, Wien. (Sonder- 

 abdruck aus : Ergebnisse der Physiologie, herausgegeben von L. Asher 

 und K. Spiro, X. Jahrgang, S. 47-215.) [Pp. 169.] (Wiesbaden: Verlag 

 von J. F. Bergmann, 1910.) 



To all who know what vegetable proteins are, it is needless to say that the name 

 of Osborne stands pre-eminent among workers with this enigmatical class of sub- 

 stances : during the nineties and the years of the present century, a regular flow 

 of communications has issued from his modest laboratory in New Haven, Con- 

 necticut, which have gained for him a world-wide reputation as the authority on 

 such matters. At first he was engaged in isolating and characterising proteins ; 

 of late years he has applied himself to the wearisome task of studying as fully and 

 exactly as possible the products of their hydrolysis and his results now rank in 

 advance of those of all other workers in the field. The present account is to be 

 read in conjunction with the author's contribution under the same title to Plimmer 

 and Hopkins' series of Biochemical Monographs (Longmans, Green Sa Co.) and 

 with the chapter he has recently contributed to Abderhalden's Biochemtsc/ie 

 Arbeitsinef/todcn. Between the present time and the appearance of Ritthausen's 

 classic work on Albuminous Substances in 1872, no attempt has been made to give 

 a comprehensive account of our knowledge of vegetable albuminoids : the appear- 

 ance of the memoir is therefore more than welcome and most opportune. It is 

 impossible to criticise such a book — those who know the writer's work and who 

 read through its pages cannot but feel that they are in the hands of the surest 

 guide of the time in a region of indescribable complexity. The advance of know- 

 ledge recorded is very satisfactory. In Liebig's day only four distinct vegetable 

 proteins were recognised ; the number was increased to ten in Ritthausen's time ; 

 now it is not possible to set a limit to the number obtainable from seeds. Latterly 

 Osborne has much improved the method of dissection by etherifying the mixture 

 of amino-acids in presence of zinc chloride at 110°; the result is a considerable 

 increase in the proportion separated of some of the constituents. It is remarkable 

 how large a percentage of the constituents of many proteins has now been 

 accounted for ; in the case of maize Zein, for example, amino-compounds amount 



