n8 RESEARCHES ON FUNGI 



Solitary and Imbricated Fruit-bodies of Polyporeae, etc. The 

 fruit-bodies of Forties officinalis (Figs. 45, 46, and 47, Chap. V), 

 F. fomentarius (Figs. 36, 37, pp. 106, 109), F. igniarius (Fig. 40, 

 p. 115), F. applanatus (Figs. 43 and 50, Chap. V), Polyporus 

 hispidus, and P. betulinus, are usually solitary. This solitariness 

 appears to be correlated with the large size of the fruit-bodies in 

 question and the downward elongation of their tube-layers. If, 

 in such species, a number of fruit-bodies were to originate in a 

 closely imbricated manner, one above the other, the hymenial 

 tubes of one fruit-body, in growing toward the earth's centre, 

 would, in the course of time, come into contact with the top of a 

 subjacent fruit-body and thus have their apertures closed. As an 

 accident, this sometimes actually happens with Fomes applanatus 

 where two fruit-bodies have arisen too near together, one above 

 the other. In Polyporus squamosus, fruit-bodies of very large 

 size are often solitary (Fig. 1, Vol. I, p. 8). Not infrequently, 

 however, in this species, several more or less imbricating fruit- 

 bodies are produced in a cluster. Under such conditions they are 

 sometimes too closely packed together, with the result that some 

 of the spores have little or no chance of being carried off by the 

 wind and, in consequence, are deposited as a white spore-deposit 

 on the tops of pilei below the hymenial tubes concerned. On the 

 other hand, in part owing to its solitariness, the large fruit-body 

 of Fomes officinalis shown in Fig. 45 (Chap. V) grew downwards 

 in the course of forty-five years for a distance of 2 feet and, 

 during all that time, was perfectly free to liberate the spores from 

 each annual tube-layer. The chances of a large fruit-body of a 

 tree-trunk-inhabiting Polyporus or Fomes having all its spores 

 carried away by the wind are certainly greatest when the fruit- 

 body stands alone, and it is therefore interesting to note the general 

 tendency toward solitariness exhibited by large fruit-bodies in these 

 genera. 



The fleshy, sulphur-yellow, annual fruit-bodies of Polyporus 

 sulphureus, so often seen in Europe upon old Oak trees, Willows, 

 etc. (Fig. 41), are, as a rule, considerably imbricated. This im- 

 brication seems to be correlated with the relatively small size of 

 each fruit-body and the shallowness of the layer of hymenial tubes. 



