394 RESEARCHES ON FUNGI 



In having a pseudorhiza which is persistent and perennial, 

 Collybia fusipes gains a distinct advantage, for thereby it economises 

 fruit-body material and so, in the end, increases its output of 

 spores. As we have seen, the mycelium lives in a buried root and 

 produces new stipe-shafts and pilei subaerially each year. If the 

 new fruit-bodies produced in successive years by a single mycelium 

 were each to develop a full-length pseudorhiza stretching upwards 

 from the buried root to the surface of the soil, a great mass of fungus 

 material would be expended in pseudorhizal production that is 

 actually saved by the first-formed pseudorhiza and its branches 

 being persistent and perennial {cf. Fig. 195, p. 390). There can be 

 but little doubt that the fungus material saved by using the same 

 pseudorhiza over and over again in successive summers is applied 

 to the production of additional or of larger fruit-bodies and, there- 

 fore, to the production and liberation of millions of additional 

 spores. Thus the persistence of the pseudorhiza of Collybia fusipes 

 is a factor of considerable importance to the fungus in its struggle 

 for existence. 



The annual pseudorhiza of Collybia radicata and the perennial 

 pseudorhiza of Collybia fusipes are comparable wdth the annual 

 fruit-body of Polyjwrus squamosus and the perennial fruit-body 

 of Fomes applanatus respectively. The perennial pseudorhiza and 

 the perennial polyporous fruit-body must be considered as having 

 been derived in the course of evolution from their annual counter- 

 parts in allied species, and therefore, as representing advances in 

 specialisation and adaptation of structure to function. There can 

 be no doubt that the persistence of the fruit-body in Fomes 

 applanatus is a great economy and enables very many more spores 

 to be produced than would be possible were it necessary to renew 

 the fruit-body flesh in its entirety each year. Thus the persistence 

 of the pseudorhizal portion of the fruit-body of Collybia fusipes 

 and the persistence of the whole fruit-body in Fomes applanatus both 

 serve to increase the number of spores produced and liberated, and 

 therefore make for greater efhciency in the process of reproduction. 



Sarcoscypha protracta. — This Discomycete (Fig. 197), as 

 already set forth in a previous Chapter, ^ resembles Collybia fusipes 



1 This volume, pp. 239-240. 



