ZOOLOGY, AND BOTANY, MICROSCOPY, ETC. 22:5 



Destruction of Biich and other wood by Polyporus nigricans.* 

 Ivar Lindroth gives an account of the attack of this fungus not only 

 on birch, but also on Salix Gaprea and Populus tremula. Infection 

 follows probably on deep wounds caused by frost, the breaking of 

 branches, etc., enabling the fungus to reach the pith ; the tissue surround- 

 ing the diseased spot becomes filled with gum. The author describes the 

 gradual destruction of the cells by the fungus, and he also notes other 

 species of Polyporei that attack the birch. 



Notes on the Variability of Hypothele repanda.f — Howard J. 

 Banker has reviewed the different accounts of this species, known 

 generally as Hijdnum repandum. It varies so much in habit and colour 

 that it has been split into three species, which the writer thinks may 

 probably become well-established. He describes a form he himself 

 found with flattened teeth, growing in comparatively wet ground. In a 

 drier situation the same fungus was found showing very few of these 

 flattened teeth, or in some cases none at all. 



Spore Dispersion in the Basidiomycetes, and the Biological Value- 

 of the Basidium.J — Richard Falck has answered a number of interesting 

 questions in the course of his investigation. He finds that pileate fungi 

 scatter their spores over a fairly wide area, even in enclosed chambers,, 

 which are secure against air-currents ; and that the larger the fungus is, 

 or the more of them there are together, the further are the spores dissemi- 

 nated. He notes also that while the Polyporei deposit the spores in some- 

 what symmetrical fashion, from the Agaricineae they are carried away and 

 deposited in lines and streaks that have no connection with the direction 

 or form of the gills. In all fungi the spore deposit corresponds to some 

 extent with the incidence of the rays of light. He has found that the 

 fungus, by its own internal heat, establishes delicate air-currents, which 

 suffice for the very wide-spread scattering of such light bodies. When 

 the spores separate from the sterigmata, they fall first downwards, and 

 are thus caught away by the currents and finally deposited, always on the 

 upper surface of the area on which they alight. These self-engendered 

 currents explain the wide dispersal in the enclosed room. The author, 

 by experiments with light and temperature, found that their influence 

 explained the lines and streaks formed by the falling spores. The 

 character of the surface on which the spores alighted had no connection 

 with these lines. Falck does not fail to allow full weight also to the 

 air-currents due to wind and temperature. 



The biological value of basidia are next considered ; the author 

 compares the different forms of fungi with reference to their sporophores ; 

 the basidium in this group of fungi suffices to raise the spores above the 

 hymenium, and so enables them to fall free when they are ripe, and to 

 be carried away by the lightest of currents. 



The author devotes considerable attention to the problem of spore 

 dissemination among the Uredineas. The teleutospores are to be found 

 on plant remains that have fallen to the ground and there passed the 



■* Naturw. Zeitschr. Land* Forstw., ii. (1904) pp. 393-40H (7 ii<>s.). See also 

 Bot. Centralis, xcvi. (19(14) pp. (324-5. t Tonvya, iv. (1904) pp. 113-7. 



t (John's Beitr. Biol. PtL.nzen, ix. (1904) pp. 1-S2 (6 pis.). 



