156 SCIENCE PROGRESS 



Lecithin and Allied Substances : The Lipins. By Hugh Maclean, M.D., 

 D.Sc. (Monographs in Biochemistry.) [Pp. vii + 206.] (London : 

 Longmans, Green & Co., 1918. Price 7s. 6d. net.) 



An ether extract of a tissue or organ is likely to contain a mixture of a number of 

 different substances which may be classified as follows: (1) Neutral fat or fatty 

 acid ; (2) cholesterol and pigments not chemically related to fats ; (3) sub- 

 stances, such as lecithin, containing fatty acids, nitrogen, and phosphorus ; 

 (4) substances containing fatty acids, nitrogen, and a carbohydrate complex, but 

 no phosphorus. The two latter groups, to which Thudechum gave the names of 

 Phosphatides and Cerebrosides respectively, are frequently classed together as 

 lipoids, but this term is by some authors made to include cholesterol and similar 

 bodies. Overton, on the other hand, uses the term lipoid in a general sense to 

 denote all cellular components soluble in organic fat solvents, such as chloroform 

 or ether. To avoid confusion the present author proposes to do away with the 

 word lipoid altogether and to replace it by Lipin, which term is to include only 

 groups (3) and (4). The classification adopted in this monograph is practically 

 that of Thudechum. The Phosphatides fall into three groups according to their 

 nitrogen phosphorus ratio as follows: (1) Monoamino monophosphatides, (a) 

 Lecithin, (b) Kephalin ; (2) Diamino monophosphatides — Sphingomyelin ; (3) 

 Monoamino diphosphatides — Cuorin. The Cerebrosides are only two in number, 

 namely, Phrenosin and Kerasin. 



The subject-matter is divided into eight chapters ; two of these are devoted to 

 the chemistry methods of extraction and purification of the phosphatides, on 

 all of which questions the author's own researches enable him to speak with 

 authority. Next follows a chapter on the Cerebrosides, and then one dealing 

 with the subject of Protagon, which, after a full description, is dismissed as 

 "nothing more than a mixture of cerebrosides and sphingomyelin with traces 

 of other bodies." Chapter VI. gives an account of a number of alleged lipins 

 such as carnaubon, jecorin, and other "insufficiently characterised substances." 

 The latter is an excellent description for many of the substances described by 

 workers in this extremely difficult field of chemical physiology. Many of the 

 results obtained by different workers are ambiguous or conflicting, and with 

 regard to the biological significance of the lipins, practically nothing is known. 

 Starting with such unpromising material, the author has nevertheless managed to 

 create order out of chaos, and he is to be congratulated on having written a very 

 clear and intelligible account of the present state of our knowledge of this 

 intricate subject. 



P. H. 



GEOLOGY 



Volcanic Studies in Many Lands. Being Reproductions of Photographs taken 

 by the Author. By Tempest Anderson, M.D., B.Sc, Hon. D.Sc. The 

 Text by T. G. Bonney, Sc.D., LL.D., F.R.S. Second Series. [Pp. xv + 

 88, with 82 plates.] (London : John Murray, 1917. Price i$s. net.) 



The late Dr. Tempest Anderson was for many years our most successful 

 photographer of volcanic phenomena. Early in 1903 his first volumes of Volcanic 

 Studies was published, containing the more interesting results of eighteen years' 

 work. Soon afterwards he retired from medical practice, and was thus able to 

 extend his travels much farther afield. At various times he visited" and photo- 

 graphed volcanoes in Mexico, Guatemala, New Zealand, Samoa, Hawaii, Java, and 

 Luzon. It was during the return voyage from the East Indies that he caught 



