674 SCIENCE PROGRESS 



familiar with its general principles, and in the limited space of some fifty 

 pages the author has succeeded in presenting clearly and attractively the 

 more important scientific and technical developments which have taken 

 place during recent years, and the many problems which still await solution. 



The first chapter deals with the production of rubber and shows the 

 striking increase in the demand for rubber, due to the development of 

 motor transport. The various questions, such as the yield of latex, methods 

 of tapping, coagulation, and quality of the product, are discussed, and 

 reference is made to the commercial possibilities of the drying oil expressed 

 from the hevea seeds. 



The subsequent portions of the book are devoted to the properties of 

 rubber itself and some of the outstanding problems arising in the course 

 of its conversion into useful articles. Amongst other matters, the latest 

 investigations on such questions as the constitution of rubber, stress-strain 

 curves, correct " cure," synthetic rubber, vulcanisation and vulcanisation 

 accelerators, the efiect of the particle size of compounding ingredients on the 

 physical properties of the rubber, and accelerated ageing tests receive brief 

 and critical notice. 



Those engaged in specialised work, from the nature of things, must be 

 liable to become parochial in their views, and for this reason clearly written 

 surveys covering a wide field meet a need which is not filled by the larger 

 work of reference. From this point of view the present little book may be 

 heartily recommended to all interested in the scientific problems connected 

 with rubber and the development of an important modern industry. 



B. O. PORRITT. 



Researches on Fungi. Vol. II, Further Investigations upon the Production 

 and Liberation of Spores in Hymenomycetes. By A. H. Reginald 

 BuLLER, B.Sc, D.Sc, Ph.D., F.R.S.C. [Pp. xii + 492, with 157 

 figures in the text.] (London : Longmans, Green & Co., 1922. Price 

 255. net.) 



The first volume of Prof. Buller's Researches on Fungi appeared in 1909. 

 In this work new fields of research were opened and new methods were 

 applied to what proved an extremely interesting and stimulating subject. 

 In the thirteen years that have elapsed since the publication of that very 

 valuable piece of biological work, Prof. Buller has been engaged in further 

 observations and ingenious experimentation, and has accumulated results 

 sufficient to fill three new volumes, of which this is the first. The earher 

 volume dealt with the biology and physics of spore dispersal in the Hymeno- 

 mycetes, with observations on spore discharge and dispersal in the Ascomy- 

 cetes and Pilobolus. 



In this new volume Prof. Buller deals in an even more detailed manner 

 with the economy of the fruit-bodies of PancBolus campanulatiis , Stropharia 

 semiglohata, and Psalliota campesiris, all fungi which belong to one of the 

 subtjrpes into which he has divided the non-deliquescing Hymenomycetous 

 fruit-bodies. In all these forms the gills exhibit mottling due to the spores 

 in difierent areas on the gills ripening at difierent times. The author has 

 observed, using a new direct method, the development of basidiospores on 

 particular areas of the hymenium, and by this and other means has been able 

 to construct figures which he claims are the first to give a correct idea of its 

 structure. He has given further proof that no basidium is able to form more 

 than one set of spores and that these spores are discharged successively. 

 As to the exact method of spore discharge, he seems less sure than in his earlier 

 work, and is of the opinion that much more research is required into the 

 nature of the attachment of the spore to the sterigma before any conclusions 

 can be arrived at. He draws attention to the existence of a hilum in spores 



