February 6, 1896] 



NATURE 



315 



OUR BOOK SHELF. 



Etude chimique du Glycogine chez les Champignons et les 

 levures. Par Dr. G. Clautriau, Assistant a I'institut 

 botanique, Universite de Bruxelles. (Hayez, 1895.) 



The absence of starch from the tissues of the fungi 

 has been generally considered as correlated with their 

 inability to form carbohydrate food material from the 

 CO^ of the atmosphere, and for a long time it was 

 considered that such carbonaceous reserve materials as 

 they possessed existed only, or at any rate chiefly, in the 

 form of fatty or oily bodies. Within comparatively 

 recent years it has been shown by Errera and other 

 observers that this does not represent the whole of the 

 facts, and that though starch is absent, a very nearly 

 allied body, glycogen, replaces it. The work under 

 notice is a record of some very careful researches, carried 

 out at the Botanical Institute at Brussels, to ascertain the 

 true nature of this glycogen, and whether it is identical 

 or no with the glycogen found in the liver and muscles 

 of many animals. 



The chief obstacle in the investigation is due to the 

 peculiar nature of the vegetable organism. Apart from 

 the question of extracting a material like glycogen from 

 a tissue in which cell membranes form a very prominent 

 feature, there remains the difficulty that very many of 

 the decomposition products of cellulose are dissolved by 

 the same solvent, and form mucilaginous material which 

 it is extremely difficult to separate later from the extract 

 of the fungi. The author of the book has with very 

 great pains elaborated a method which enables him to 

 prepare the glycogen in a pure state, and without a very 

 great loss of material. The details of his process are too 

 long to narrate in full ; they may be briefly indicated by 

 saying that the fungus is dried at a sufficiently high 

 temperature to destroy the enzyme which is present 

 with the carbohydrate, and reduced to powder by various 

 means. The powder is repeatedly extracted with dilute 

 caustic potash solution till no more glycogen is dissolved. 

 The mucilaginous matter is got rid of by causing an 

 inert inorganic precipitate to be formed in the solution 

 which carries down the mucilage, but leaves the glycogen 

 in solution. The latter is then purified, by treatment 

 which is very fully detailed. 



The glycogen has been thus prepared from many 

 species of fungi, including Boletus, Amanita, Phallus 

 and others, also from several yeasts. 



Prepared thus, and examined side by side with the 

 animal product obtained from the liver of the rabbit, 

 the two appear to be identical. The solutions are faintly 

 opalescent, and deflect the plane of polarisation to the 

 same extent in the two cases. Both yield maltose when 

 acted on by saliva, and dextrose when boiled for some 

 time with weak mineral acids. Their percentage com- 

 position is the same, corresponding, according to the 

 author, to the formula 6(C6Hiq05)-|-H20. 



The latter portion of the work is devoted to an 

 examination of the chemical and physical properties of 

 glycogen, particularly its relation to iodine, with which 

 it gives a characteristic brown colouration. 



Dr. Clautriau is to be congratulated on making a valu- 

 able contribution to our knowledge of the carbohydrate 

 metabolism of the group of plants with which he has been 

 engaged. 



Popular Telescopic Astronomy. By A. Fowler, A. R.C.S., 

 F.R.A.S, Pp. vi + 77. (London : George Philip 

 and Son, 1896.) 

 Astronomy has no direct bearing upon industry, there- 

 fore it is neglected in this utiHtarian age. Technical 

 education is made to include such subjects as political 

 economy, problems of poverty, and great painters; 

 but the authorities which decide what is or is not tech- 

 nical knowledge, draw a line at celestial science. The ' 



NO. I 37 I, VOL. 53] 



result is that astronomy is more studied for its own sake 

 than any other science. But by merely reading popular 

 astronomical literature, it is not possible to obtain a truly 

 scientific knowledge of the heavenly bodies ; personal 

 observation of the varying aspects of the midnight sky, 

 and of the chief characteristics of celestial objects is 

 essential practical work compared with which book learn- 

 ing is as nothing. Two obstacles have hitherto prevented 

 a wide enjoyment of the beauties of celestial scenery — 

 first, the prohibitive prices which opticians charge for 

 even small telescopes ; and secondly, the absence of 

 small and trustworthy guides to the heavens, suitable for 

 those who have no idea what to seek and where to look. 

 There are several most valuable works for the initiated 

 amateur, but few are of a kind that the unexperienced 

 observer finds intelligible. Mr. Fowler's little book 

 removes both the obstacles referred to. In the words of 

 the sub-title, it is a book showing " how to make a 2-inch 

 telescope, and what to see with it," and very admirably is 

 the promise of the title-page fulfilled. The telescope 

 described is made by each student in the course of 

 Astronomical Physics at the Royal College of Science, 

 South Kensington. By following out the instructions 

 given, a serviceable instrument can be constructed, 

 capable of bringing into view a multitude of stars 

 and sights beyond the range of the unaided vision. 

 There can be no doubt that whoever makes his own tele- 

 scope, not only performs thereby a valuable exercise in 

 optics, but he is not likely to make such foolish mistakes 

 as the astronomical tyro who procures his polished instru- 

 ment from the opticians, and looks upon it as akin to a 

 box of tricks. 



Two chapters of the book are taken up with the details 

 of the construction of the telescope, and hints on the 

 practical use of it. Then come descriptions of star 

 seasons, accompanied by four maps showing the chief 

 constellations ; and the remaining seven chapters are 

 devoted to observations of the sun, moon, planets, comets, 

 stars, double stars, star-clusters, and nebulae. The whole 

 of the work explained can be easily understood and 

 readily performed. The book is practicable as well as 

 practical ; every instruction in it can be carried out, 

 every observation described bears the impress of ex- 

 perience. Astronomy will gain more by the publication 

 of this little volume than by the issue of a score of works 

 of a descriptive character. 



Anleitung zur Molekulargewichtsbestitntnung. Von Dr. 

 Gotthold Fuchs. (Leipzig : Wilhelm Engelmann, 1895.) 

 This little book of 41 pages is specially written as a 

 laboratory guide to the methods of determining molecular 

 weights from observations of the freezing-point and boil- 

 ing-point of solutions made by means of the Beckmann 

 pieces of apparatus. It contains short historical accounts 

 of the theory of the two methods, and descriptions of the 

 apparatus, including the latest modifications, and the 

 modes of making the observations. Lists of data for 

 calculating results when using different solvents, and 

 numerous examples of the kind of values obtained, taken 

 from Beckmann's papers, are also included. The author 

 is careful to direct attention to the anomalies likely to be 

 met with, and has succeeded in writing a trustworthy 

 account of the present condition of these two widely 

 used methods. J. W. R. 



Recettes de r^lectricien. By ]£. Hospitaller. Pp. vi + 



352. (Paris: G. Masson, 1895.) 

 An electrician's pocket-book, full of workshop receipts, 

 and containing numerous hints of use in electrical labora- 

 tories. In the selection of the receipts, the author has 

 exercised discretion, and in their arrangement he shows 

 that he understands exactly the requirements of electrical 

 artificers and engineers. 



