930 



NA TURE 



[UECIiMBlK 29. 1923 



biologist, and it is a fact, however unfortunate, that 

 the great majority will not read a foreign language 

 unless they must. The translation is direct and ade- 

 quate, and reads smoothly, although a few Germanisms 

 might be got rid of in a second edition. 



Work on the prolilems of sex is proceeding so rapidly 

 that Doncaster's and Morgan's books on the subject, 

 although not ten years old^ are cjuite out-of-date. We 

 have no hesitation in recommending Goldschmidt's 

 work ns the best existing introduction to the subject, 

 and Icndfring our thanks to Prof. Dakin fnr his transla- 

 ti-iii, Julia- 



Chemistry of Urea and Resins. 



(i) The Chemislry of Urea: The Theory of its Consti- 

 tution, and oj the Origin and Mode of its Formation 

 in Living Organisms. By Prof. Emil A. Werner. 

 (Monographs on Biochemistry.) Pp. xii + 212. 

 (London : Lonj,'mans, Green and Co., 1923.) 14^. 

 net. 



(2) Synthetic Resins and their Plastics. By Carelton 

 Ellis. Pp. 514. (New York : The Chemical 

 Catalog Co. Inc., 1923.) 6 dollars. 



(i)" I "'HE monograph oh urea differs somewhat 

 JL in scope from others of this series of which 

 it forms a part, inasnim li as it deals almost exclusively 

 with one compound. Its importance, however, in 

 animal and vegetable life is unquestioned, and no one 

 will feel that a whole volume devoted to this topic 

 is an unnecessary addition to biochemical literature. 

 The subject-matter is divided into two sections : the 

 first treats of the synthesis and constitution of urea ; 

 the second with its origin and occurrence in Nature. 



There is no one more competent to write on urea 

 than the author, who for many years past has attempted 

 to unravel its structure. A considerable portion of 

 the first section is concerned with this problem, and it 

 must be confessed that Prof. Werner has made out 

 a strong case for the tautomeric formula 



/NHa , NH, 



HN:C 



./ 



OH 



HN:C;| 



o 



There is no doubt that the majority of changes which 

 urea undergoes with different reagents and by heating, 

 such as the formation of biuret, and the conversion 

 of ammonium cyanate into urea, wliich is represented 

 thus : 



NH, 



ILN.O.CNll 



/ 



NH, 



PI . O . CN :t HN : C : O 



HN:C;! 



O 



may be equally well explained by the new formula. 

 Moreover, the formation of cyanuric acid and the 

 NO. 2826, VOL. 1 12] 





action of alkalis rc' ■ uch simpler interpretation 



in this way. 



(3) As a rule, an organic chemist, when confronts 1 

 in the course of an investigation n 

 product, is discouraged from exami 

 It is an amorphous, intractable material which gent r 

 ally defies crysUillisation and, consequently, the only 

 satisfactory means of purification. It is therefore con- 

 signed to the scrap heap. The technical chemist, 

 the other hand, whose business it is to mam;' * 

 varnishes and composite materials, such as p; 

 inks, paper and cloth size, linoleum, etc., far iran 

 despising such products, is able to utilise many so- 

 called synthetic resins on a very considerable scale. 

 The volume under review gives a very comprehensive 

 account not only of the production and use of synthetic 

 resins ; but also a detailed description of the machinery 

 u.sed in their application. He tells us tha' 

 diminishing supply of natural resins, or gums, .... .... 



trade prefers to call them, has been viewed, with ap- 

 prehension during past years by varnish manufacturers 

 and other large consumers of such products." 



It appears that the introduction of phenol-formalde- 

 hyde and cumarone resins has opened up a new field 

 for the synthetic organic chemist. There is a remark- 

 able variety of substances now employed and derived 

 from such products as glycerin and phthalic acid, 

 vinyl polymerisation products, urea and thiourea 

 derivatives and sulphur phenol resins. The author 

 advises the chemist to scrutinise carefully every nr - 

 resin he may obtain and record its formation. H« 

 is a new and interesting field of operations, and insteaii 

 of feeling thwarted in his aim, the organic chemi>t 

 may in future turn what he formerly regarded as .1 

 failure into a possibly lucrative succes- j I! ( 



Micrography as a Fine Art. 



Botanical Pen-Portraits. By Prof. J. W. Moll and I>r 

 H. II. Janssonius. Pp. viii+472. (The Hague: 

 Martinus Nijhoff, 1923.) 30 guilders. 

 T was not until about the middle of the nineteenth 

 century that descriptions of microscopical char- 

 acters were introduced into treatises concerned witli 

 the identification of drugs. There are now several 

 books primarily designed for students of pharmacy, 

 but occasionally referred to by botanists who endea\oiir 

 to demonstrate to their students that even a knoult dr 

 of plant histology may have its economic valu 

 volume by Prof. Moll and his junior collaborator anr.s 

 at giving greater precision to the description of veget- 

 able drugs and therefore greater accuracy in their 

 identification. 



Prof. Moll has devoted himself during the last twentv 



I 



