470 RESEARCHES ON FUNGI 



converted into a large obconic or irregular dark spongy structure. There 

 is no good reason for regarding such a structure as a sclerotium. 



Usually, in the first summer of fruiting of a Collybia fusipes mycelium, 

 there comes up on a rotten root a soUtary fruit-body which has a simple 

 pseudorhiza like that of C. radicata. The pileus and aerial stipe-shaft 

 of this fruit-body then die and decay, but the pseudorhiza buried in the 

 ground persists and lives on through the winter. In the second summer 

 the pseudorhiza, at its apex, gives rise to a cluster of new fruit-bodies, 

 each of which has a pseudorhiza of its own. These new fruit-bodies 

 eventually die down except for their pseudorhizae which persist. Thus 

 in the second winter the persistent pseudorhiza is a branched structure. 

 In the third summer, the pseudorhiza may, as before, give rise to new 

 fruit-bodies, and so forth, so that, as several years go by, the pseudorhiza 

 increases in size and becomes more and more branched. 



The longest pseudorhiza of Collybia fusipes observed was about 

 lii inches in length. It was attached to a deeply buried Beech root and 

 bore a cluster of new fruit-bodies on a tertiary branch. Presumably the 

 pseudorhiza was three years old and the fruiting season was the fourth 

 in succession. 



In having a pseudorhiza which is persistent and perennial, Collybia 

 fusipes economises fruit-body material and so, in the end, increases its 

 output of spores. Thus the persistence of the pseudorhiza of C. fusipes 

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

 existence. 



It is a remarkable fact that the fruit-body of Sarcoscypha protracta, 

 a Discomycete whose mycelium vegetates in buried roots of Poplars, 

 develops a pseudorhiza which, in its persistence from year to year and 

 in its branching, exactly resembles the pseudorhiza of Collybia fusipes. 

 We are here afforded another example of two very diverse plants having 

 become adapted in the same way to meet the requirements of a similar 

 set of external conditions. 



Chapter III. — Omphalia fiavida, the cause of the American Coffee- 

 leaf disease, is a luminous and gemmiferous leaf-spot fungus. 



In pure cultures on bread and other artificial media, as Ashby first 

 observed, the mycelium produces in succession : (1) gemmifers, hitherto 

 misnamed '' stilbum-hodies,'' and (2) perfect agaricaceous sporophores. 



Each gemmifer consists of a slender, sohd, tapering pedicel about 2 mm. 

 long and of a terminal, detachable, multicellular gemma, shaped hke the 

 knob of a door-handle and about 0-36 mm. in diameter. 



The structure of a gemmifer has been redescribed in detail. The 

 pedicel is sohd, and not hollow as supposed by Puttemans. 



Each gemma is an oblate spheroid (a flattened globe) with an apo- 

 physis of smaller diameter below. Its upper surface is slightly depressed 

 in the centre. The apophysis encloses and clasps the top of the pedicel 

 about 0- 1 mm. from the pedicel's extreme end. Peripherally the oblate- 



