August 24, 1906.] 



SCIENCE. 



245 



body of the lecithin type. Some statements 

 are made of the possible sources of the 

 lecithins in feces. 



Dissociable Compounds of Mucoids and 



other Proteins: W. J. Gies. 



We know practically nothing about the 

 ways in which proteins are held in living 

 protoplasmic structures. The molecules of 

 the protein compounds are relatively so 

 large that as yet our physico-chemical 

 methods of measurement are inadequate 

 to give us correct ideas of molecular size 

 and intramolecular structure, although we 

 know much about the lifeless and, in some 

 respects, comparatively meaningless frag- 

 ments into which protein molecules may be 

 broken. Our ignorance of the funda- 

 mental biochemical relation of proteins to 

 the associated constituents of protoplasm 

 appears to be largely due to our vague 

 knowledge of the chemical statics and dy- 

 namics of true cellular proteins, a fact 

 which serves, however, as a constant stim- 

 ulus to protein investigation. Among the 

 many protein substances, the nucleopro- 

 teins and the glucoproteins are very impor- 

 tant tissue constituents. The essential part 

 of each of these natural type proteins and 

 the part to which the usual name is ap- 

 plied appears to be a colloidal organic acid. 

 The forms in whidh the acid radicals occur 

 in cells and tissues have not been definitely 

 made out, although it is natural to presume 

 that the acid radicals are united directly 

 to one or more distinctly basic radicals in 

 each case, and that variations in the char- 

 acters of such compounds are associated 

 with physiological as well as pathological 

 variations of cellular composition and tis- 

 sue function. The author has attempted 

 to get to the bottom of this complicated 

 matter by making definite salts of these 

 proteins with the aid of methods that could 

 be relied upon to leave the acid radicals 

 unchanged. 



The writer has lately prepared calcium, 

 sodium, potassium and ammonium salts of 

 mucoid by the following process: The 

 slightly alkaline solution of glucoprotein is 

 dialyzed until neutral and then poured 

 into a large excess of 95 per cent, alcohol, 

 which causes the precipitation of the mu- 

 coid. This precipitate is purified by reso- 

 lution, dialysis and reprecipitation. The 

 final product is made anhydrous by treat- 

 ment with absolute alcohol and ether. The 

 comparatively pure salts thus obtained are 

 light snow-white powders. 



The author hopes that, by increasing the 

 knowledge of artificial products, analogies 

 with natural compounds would be not only 

 more easily recognized but also the char- 

 acters of functions of the compounds in 

 living protoplasm would be more thorough- 

 ly understood. ^ ^ ^^ 

 •^ G. R. White, 



Press Secretary. 



SCIENTIFIC BOOKS. 



Leiifaden fitr den praMisch-chemischen Un- 

 terricht der Mediziner. Zusammengestellt 

 von Franz Hofmeister, Professor der phys- 

 iologischen Chemie an der Universitat 

 Strassburg. II. Aufl. Braunschweig, Vie- 

 wig u. Sohn. 1906. Pp. 136. Preis Mark 

 3.50. 



This little book admirably desci-ibes labora- 

 tory courses in qualitative analysis, organic 

 chemistry (so far as it may be of interest to 

 the physician) and in physiological chemistry. 

 The directions given for making tests are 

 brief and precise and at many places reasons 

 are given for the methods advised in making 

 the tests. In this revision it appears that 

 particular attention was given to the course 

 in physiological chemistry so that it might 

 include the results of the latest investigations 

 bearing especially upon the tests for the sub- 

 stances concerned in that branch of science. 

 In short, the book is one which excellently 

 covers the ground in practical chemistry essen- 

 tial to medical students. 



John Marshall. 



