112 Eumycetes. 



which are primarily considered from the point of view of spore 

 discharge. The present volume collects together much of the previous 

 work done by Professor Buller on this group and a considerable 

 number of results hitherto unpublished. 



In the opening chapters of the book the writer discusses the 

 efficiency of the sporophores of the Hymenomycetes as organs for 

 the formation and liberation of enormous quantities of spores. He 

 makes calculations to shew the relatively large increase of h5''menial 

 surface that is given bj^ the formation of gill plates in the Agarici- 

 neae and of pores in the Polyporeae. There is pointed out also the 

 necessity for stability of the fructiiications of these groups if spore- 

 discharge is to be effected efihciently, for, were the pileus of a mushroom 

 e. g., allowed to sway to and fro, very few of the spores would be 

 able to fall free from the gill plates. 



Another part of the book deals with correlations made by 

 Professor Bull er between the reactions of the fruit bodies of the 

 Hymenomycetes to external Stimuli such as light and gravity on the 

 one band and the general structure and habitats of these fungi on 

 the other. Thus the development of the fruit bodies of Lentinus 

 lepideus is affected both by light and by gravity, while the fructi- 

 fications of the common mushroom {Psalliota campestris) react onlj^ 

 to gravity. The former fungus grows on wood and its orientation 

 to the subStratum is indefinite so that heliotropic curvature of the 

 stipe is of obvious advantage. The latter species grows on the ground 

 the surface of which is generally horizontal over a limited area; 

 thus heliotropic reaction is unnecessary in this case. The author 

 correlates also the heliotropism exhibited by man}»^ coprophilous 

 fungi (e. g. Coprinus, Pilobolus) with the irregulär surface of the 

 subStratum on which they grow. 



The spore cloud of Polyporus squamosus is then described. Other 

 observations are recorded which shew that similar spore clouds are 

 discharged from mushrooms and allied fungi; this fact Buller has 

 demonstrated by the employment of a concentrated beam of light 

 below the sporophores at the time of maturity. 



Another series of observations deals with the power possessed 

 by genera such as Schisophyllum , Polystictiis, etc., of withstanding 

 dessication without injury. When the dixy fructifications of Schiso- 

 phyllum co7nmune are damped, spore discharge is almost immediately 

 resumed. 



The author brings forward evidence to shew that the basidio- 

 spores of Hymenomycetes are shot violently from their sterigmata, 

 though the mechanism of this proces is still obscure. A large amount 

 of work has been done on the physics of spore-fall and this botanist 

 has applied for the first time a direct test of the applicability of 

 Stokes' Law to the fall of microscopic spheres in air. 



In regard to the Coprinus type of fruit body which deliquesces 

 at maturity Buller puts forward the view that this process of 

 deliquescence is one of auto-digestion which enables successive parts 

 of the gills to liberale their spores effectively because it is found 

 that in the Coprinus type of fruit body all the basidia over a small 

 area of a gill are mature at the same time. Some authorities have 

 supposed in the past that the spores fall into the liquid produced by 

 this process of deliquescence and that insects seek this fluid and 

 so effect the dissemination of spores. 



In the closing chapters of the book the author deals with 

 observations made by him on spore discharge in certain Ascomycetes. 



