434 



NA rUR^ 



{March 7, 1889 



gums and mucilages as yield various glucoses, and some- 

 times also arabinine, as products of hydrolytic resolution 

 (gum-arabic, cerasin, bassorin, "wood gum"). Ascend- 

 ing in the scale of molecular complexity, the celluloses 

 are next described ; and lastly, in separate sub-sections, 

 lignin, cork, and pectic derivatives. We have been in- 

 terested in comparing the author's account of the latter 

 group with those given under " Celluloses " in the new 

 edition of .Watts's " Dictionary." There is a close agree- 

 ment in general method of treatment ; and it is satisfactory 

 to find that the problem of the constitution of the celluloses 

 is being worked on such lines as would be laid down from 

 a study of the general view of the carbohydrates which 

 Prof. Tollens has given us. Neither of these acounts of 

 cellulose suggests any probable constitutional formula for 

 the unit group of which the celluloses may be regarded as 

 poly-derivatives ; but, putting the views of both authors 

 together, we arrive at the following — 



CH., . CHOH . CHOH CH . CH . OH . CH, 



which we think will at least ba found of service as a 

 working hypothesis. In the section " Lignin," Prof. 

 Tollens has overlooked some of the researches of recent 

 years, which have, as the result of investigations of its 

 hydrolysis and chlorination, more definitely identified 

 the non-cellulose constituent of lignified tissue with a 

 furfuralic constitution on the one side, and the tendency 

 to an aromatic grouping on the other. In the section 

 " Cork," he has also overlooked some of Fremy's interest- 

 ing work on the constitution of "cuticular" substances 

 The concluding section of the saccharocolloids comprises 

 the pectic group of plant constituents, which are briefly 

 but fully described. 



The fourth section opens with an accoant oi arabinosc^ 

 which ihe author represents by the constitutional 

 formula — 



CH2;CHOH)3 . CHOH. 

 Foi i/iose, or polymerized formaldehyde, is not regarded 

 as a true glucose. Carius's phenose is described ; • the 

 evidence as lo its composition, however, is very slender- 

 The writer has, moreover, devoted some time to a re- 

 petition of Carius's research, but failed to obtain any 

 product such as that described. Inosite is represented 

 on the basis of Maquenne's researches,'by the symmetrical 

 formula — 



CHOH 

 /\ 

 HOHC CHOH 



I i 

 HOHC CHOH 



CHOH. 



Dambonite and bornesite, which are found in caoutchouc- 

 yielding juices, are described as the mono- and di-methyl 

 ethers of inosite, respectively. 



The fifth section comprises the hexahydric alcohol 

 mannite and its isomerides, dulcite, sorbite, and perseite, 

 of which the typical mannite is fully described. 



The second part of the work gives a detailed account of j 



" substances closely related to the carbohydrates, and ob- 

 tained for the most part from them, whic^i.are either acids 

 or acid-anhydrides (lactones), and the'Tnolecule of which 

 contains 6 C-atoms": (a) saccharinic 'acid, C^HjaOg, 

 and its isomerides, iso- and m^/a-saccharinic acids, their 

 lactone-anhydrides, CgHioOg, '''• sacchariiies^^ and their 

 oxy-derivatives, saccharones, CyHgOg ; {b) gluconic acid, 

 QiHijOy, and its isomerides, galactonic and arabinose 

 carbonic and mannitic acids ; saccharic acid, CgHi^Og, 

 and its isomerides, mucic, iso-, meta-, and para-saccharic 

 acids, with their lactoftic and other derivatives. 



Such is a brief account of the contents of the biok 

 before us. The main purpose is necessarily the theoreti- 

 cal treatment of the subject — from, the point of view, that 

 is, of pure chemistry ; at the same time due prominence is 

 given to technical considerations, and the physiological 

 aspects of the subject are by no means excluded. 



We do not believe that we are yet within measurable 

 distance of a knowledge of the actual molecular con- 

 stitution of the carbohydrates. We do not even think 

 that the evidence for the C,. formulce of the simplest 

 members is at all conclusive. One of the assumed 

 criteria of this point— the calculation of molecular weight 

 from the lowering of the freezing-point of solvents by the 

 presen:e of compounds in solution, as proposed by 

 Raoult— is not mentioned by Prof. Tollens. At a recent 

 meeting of the Chemical Society, Messrs. Brown and 

 Morris communicated the results of an investigation of 

 the freezing-point of solutions of the simpler carbohydrates, 

 which appear to confirm the generally accepted views. 

 Nevertheless, it wouW be premature to pronounce at all 

 positively, either as to this particular criterion, or as to the 

 evidence generally on these points. 



The chemistry of the carbohydrates brings us into 

 contact with the syntheses and transformatioas of the 

 organic world. The plant is, and will remain through 

 all time, the chemist's ideal. Every contribution to the 

 chemistry of the carbohydrates is a step towards a com- 

 prehension of the chemistry of elaboration. The num- 

 ber of workers in the field is relatively small, but will 

 increase as the methods of investigation are rendered 

 more precise. It is from this point of view that we com- 

 mend this little work to the notice of all who have either 

 a special or general interest in plant-chemistry. 



BRITISH MOSSES. 

 British Mosses. By F. E. Tripp. 2 Vols. New Edition. 



(London: George Bell and Sons, i8S8.) 

 HP HE fact that a new edition of this work has been 

 -*- called for shows that thfese elegant plants have a 

 wide-spread circle of admirers, and that there are many 

 seekers after a knowledge of their structure. 



The introduction occupies thirty-eight pages. In Sect. 

 I, on the homes of mosses, we have a highly poetical 

 description of the third day of Creation, and production 

 of vegetation according to Genesis. This is followed by 

 the natural distribution and habits of the mosses ; and by 

 charming word-pictures of woods and moorlands the 

 authoress compels her readers to accompany her and see 

 for themselves the beauties that await observation on every 

 side and at every season. 



Sect. 2, the characteristics of mosses, is written in 



