54 PEOCEBDIN'GS OF THE 



iiitHiisily and diivclion ot" light, and since the direction of move- 

 ment may be determined as the resultant of the varying pliysico- 

 chemical activities in the whole of the .sensitive region, we must 

 conclude that butli intensity and direction of light are necessary 

 factors in the pliot()lro|)ic response. 



Dr. Waueu then read his second paper entitled " iSpore- 

 Coloralion in the A-garicacea)." He stated that the use of spore- 

 coloration as a basis for the classification of the AgaricaceaB is 

 artiticial and impcirfect. There is no clear line of demarcation 

 between the various colours, and the designation of the colours in 

 the text-books is very iinletinite and unsatisfactory. 



A beginning has, however, been made by members of the Myco- 

 logical Committee of the Yorkshire Naturalists' Union to obtain 

 more accurate records of spore-coloration in terms of a standard 

 series of tints, such as that of the ' Code des Couleurs,' by 

 Klincksieck & Valette (Paris, 1908). 



We liave already found — aud this may be a fact of some con- 

 siderable physiological interest — that, with one or two doubtful 

 exceptions, all the spore colours so far standardized, whether pink, 

 rusty, or purple, fall within the region of the less refrangible half 

 of the spectrum. Spectroscopic examination also shows this. 



It has been suggested by B idler that these colouring- matters 

 may serve a useful purpose by screening off certain of the sun's 

 rays from the living protoplasm. 



If this is so, we ought to find some support for the hypothesis 

 in the more abundant distribution of the coloured-spored species 

 in the open and of the white-spored forms in the shade. On 

 tabulating tlie records of habitats, it has been found that we get 

 approximately : — 



Black-spored forms : 1^4" /o occurring in the shade, 76% in the open. 

 Purple „ „ 307o „ „ 707„ 



White „ „ 90% „ „ 10% 



These figures support the hypothesis. 

 The pink-spored forms gave : — 



347o iu the shade, QQ"/o in the open. 

 This is intermediate, as might liave been expected, between the 

 dark-spored and the wliite-spored species. Tbe brown or rusty- 

 spored forms, however, gave figures not quite so good, viz. : — 



527o ii^ the shade and 487„ in the open. 



These figures are only approximate, however, as they are com- 

 piled from a list of habitats which is probably not very accurately 

 determined as regards light and siiade. 



S|i(ire-colorati()n may, however, dej)end, partly at least, upon 

 the kind of substratum on whii-h the Kungi gro^v . It is significant, 

 for example, that a lart^e proportion of the black-sjiored forms 

 grow upon dung, whilst the white-spored forms are found largely 



