i 4 RESEARCHES ON FUNGI 



theory of the primitiveness of blackness as a spore colour loses 

 its chief support. 



On general grounds, I am inclined to regard colourlessness as 

 the most primitive condition in spores. We may well believe that 

 at first the conidia were as colourless as the basidia off which they 

 became constricted. It seems to me probable that the various 

 pigments were only gradually developed, possibly by a series of 

 mutations. Many so-called black spores are not truly black ; thus 

 in Gomphidius the spores are smoky-olive, and in Copvinus atra- 

 mentarius the spore powder has a brownish tinge. Intermediate 

 gradations of this kind seem to suggest that blackness in spores 

 was not acquired all at once but step by step. This view is further 

 supported by ontogeny. Thus in Copvinus comatus the spores 

 when very young are colourless ; they then become pinkish, and 

 thereby turn the gills pink ; they then gradually become black. 

 In many species of Coprinus the spores whilst ripening become 

 brown, and the brown colour then gradually deepens into black. 

 As further support for the view that colourlessness in spores is a 

 primitive feature in Hymenomycetes, may be mentioned the fact 

 that five out of the six genera of Hypochnacere, 1 as well as such 

 a primitive genus of Thelephome as Corticium, have unpigmented 

 spores. 



No suggestion has yet been made as to the significance of the 

 colours of spores. It is certain that some colouring matters, e.g. 

 those of heart-wood, of sclerenchymatous strands in the rhizomes 

 of ferns, of carrot roots, and of the rhizomorpha subterranea of 

 Armillaria mellea, cannot be of ecological value, since they are 

 developed in organs not normally exposed to the light. Possibly, 

 too, the colouring matters of spores are useless so far as their 

 colour properties are concerned : they may be merely bye-products 

 of certain metabolic processes. However, it will shortly be shown 

 that sunlight is injurious to the spores of certain Hymenomycetes. 

 It therefore seems possible that the various colouring matters 

 deposited in spore walls may be of value in that they serve to 

 absorb injurious rays of light, thus preventing them from reaching 

 the living protoplasm. If coloured spore walls are useful in filtering 

 1 P. Hemiin^s, lo<: cit., p. 114. 



