Giissow : The Canadian Tuckahoe 105 



sclerotium differs in color perceptibly from the interior. There 

 is a pronounced coal-black layer readily distinguished from the 

 interior substance. The bark seems structureless in our speci- 

 mens ; on microscopical examination one finds but the debris of 

 what might have been originally specialized hyphae. 



The interior is blackish olive green, particularly when fresh, 

 becoming more grayish black when dry, but its appearance on the 

 whole is black, interspaced with many small crevices which are 

 filled with dirty, white, very tough masses of hyphae. This gives 

 the interior a mottled, marble-like effect. (Plate 7, center.) 



Microscopically examined, the hyphae are of very irregular 

 thickness. They are thick-walled and show numerous curious 

 hooks and clamps and an occasional anastomosis. (Plate 9-^.) 



The darker substance, which resembles rubber, evidently also 

 consists of hyphae, considerably thicker and almost solid when 

 moistened. The difference in size between the hyphae composing 

 the light and dark masses, is plainly shown in our attempt to 

 interpret the interior structure of these sclerotia. (Plate 9B.) 



When thoroughly dry, the sclerotia became as hard as stone 

 and once they had dried out would not produce any fruiting 

 bodies, but merely decomposed when buried in the soil. 



The habitat of these sclerotia is invariably among the roots 

 of poplar woods. They are found generally after land has been 

 cleared and the ground backset afterwards by the plough. Cor- 

 respondents frequently report having seen them attached to roots. 

 This has given rise to the statement that they might be parasitic. 

 The wood to which the sclerotia are attached is filled with hyphae, 

 but we have no first-hand evidence that they derive more benefit 

 from being attached to a root — although there exists such prob- 

 ability — than from the stones with which they are often intimately 

 associated. 



The next striking statement is that these bodies are edible, but 

 we ourselves could not exert any marked effect on them w^th our 

 teeth, though in the interests of mycophagists we tried them raw 

 and cooked. Cooked, they became slightly jellified, but a jelly 

 itself was not produced. 



The late James Fletcher (i) gave a preliminary account of his 



