246 Eumycetes. — Pflanzenkrankheiten. — Lichenes. 



Biology and Classification. (Cambridge University Press, 

 1913. Demi 80. 412 pp. 290 lextill. Price 14 sh.) 



The present volume provides the Student wiih an up-to-date 

 account of the British Uredineae, and may thus be said to replace 

 Plowright's "Monograph" which has for many years been out 

 of date. 



The work is divided into two parts, general and systematic. 

 The former is largely biological. The life-histories of various types 

 of rusts are given, and there are chapters on sexuality, nuclear 

 division, specialization, immunity, phylogeny and Classification. The 

 description in the second part are based on those of the Sydows 

 "Monographia Uredinearum" and the nomenclature is that of the 

 International Rules. The species are arranged in the order of the 

 families and genera on which they are parasitic. The principal 

 synonomy is supplied and practically all species are figured. Critical 

 work has shown that several species, have had to be excluded from 

 the British flora, but many others have been recently recorded for 

 the first time. There is one novelty Puccinia secalina a biologic 

 species of P. dispersa. A. D. Cotton. 



Brooks, F. T., Silver Leaf Disease. (Journ. Board Agric. XX. 

 8. p. 682—690. 1913.) 



A general account of Silver Leaf disease in Britain and also 

 the methods of treatment. Although Silver Leaf is a manifestation 

 of ill health now known to be due to various causes, the author 

 is able to State that from the fruit grower's point of view Stereum 

 purpureum is undoubtedly the principal agent. A. D. Cotton. 



Fink, B., The nature and Classification of lichens: IL 

 The liehen and its algal host. (Mycologia V. p. 97—166. 

 May, 1913.) 



This is the second and concluding portion of an elaborate 

 review of the subjects indicated in the title. The summary and 

 conclusions reached by the author are stated as follows: 



1. There has hitherto been no agreement regarding the nature 

 of the liehen, and the only thing about the problem generally be- 

 lieved by botanists is that the green and blue-green cells in lichens 

 are algae. 



2. Due probably to clinging to traditional phraseology, most 

 botanists are not able to express themselves consistently with respect 

 to any view that they may hold relative to the nature and the 

 proper treatment of lichens. 



3. The text-book Statements about lichens are rarely coherent, 

 excepting those that cling to an entirely traditional and erroneous 

 Position. 



4. The fundamental problem coneerns the nature of lichens, 

 and this must be settled before we can hope to agree regarding 

 the Classification of these plants. 



5. Due to peculiar ideas about the relation of the liehen to its 

 algal host, this problem of relationship has become the main part 

 of the eonsideration of the nature of the liehen. It is therefore 

 treated at length in this paper. 



6. Recent researches prove that all hypotheses of mutualism 



