38 RESEARCHES ON FUNGI 



roots with which it comes into contact, and thus spread infection 

 locally.-^ 



In Coprinus domesticus ( = C. radians, Fig. 25, p. 43) we have 

 an ozonium {Ozonium auricomum Link, O. radians Persoon)^ which 

 is very similar to that of Psathyrella disseminata. As already re- 

 marked, this ozonium is often to be found in the autumn under and 

 upon the bark of fallen trees, particularly Elms. Owing to shrinkage 

 of the wood and other causes, the bark of such trunks and logs often 

 becomes loose. The ozonium flourishes in the space between bark 

 and wood. One may suppose that : (1) not infrequently, the 

 primary infection of a tree-trunk or log takes place at one spot ; 

 that (2) the ordinary vegetative mycelium then soon gives rise to 

 an ozonium which rapidly makes its way in the open space under 

 the bark ; and that (3), as a result, the tree-trunk or log becomes 

 infected at ever greater distances from the original seat of infection. 

 I also suspect that the ozonium is able to grow through the soil in 

 somewhat the same manner as that of Psathyrella disseminata. 



The second function of the ozonium — that of enabling the fruit- 

 bodies to arise in positions suitable for the successful production 

 and liberation of spores — will now be discussed. So far as Psathy- 

 rella disseminata is concerned, a glance at Figs. 18, 19, and 20, will 

 show the great advantage there was in the fruit-bodies arising not 

 directly on the stump itself, but upon the ozonium penetrating 

 through the soil. The two or three thousand fruit-bodies, had they 



^ Robert Hartig, Wichtige Krankheiten der Waldbdtime, Berlin, 1874, pp. 27-29; 

 also Lehrbuch der Pflanzenkrankheiten , Berlin, 1900, pp. 189-190, and Fig. 185. 



^ By Persoon, Link, and other botanists of a century ago the ozonium of 

 Coprinus domesticus, like the rhizomorpha subterranea of Armillaria mellea. was 

 believed to be an independent species of fungus. In 1888, Quelet (Flore 

 Mycologique de la France, Paris, vol. i, 1888, p. 48) asserted that it is only the 

 mycelial condition of Coprinus domesticus (his C. radians). Then, in 1901, Plowright 

 (" Ozonium auricomum Link," Trans. Brit. Myc. Soc, vol. i, 1901, pp. 181-182) 

 confirmed this view by observing that the ozonium which had grown from a block 

 of wood into the basal hole of a flower-pot containing an Aspidistra produced fruit- 

 bodies of Coprinus domesticus at the top of the soil. Finally, in 1914, the connec- 

 tion of Ozonium auricomum and Coprinus domesticus was clearly demonstrated by 

 F. T. Brooks (" Observations on pure cultures of some Ascomycetes and Basidio- 

 mycetes," Trans. Brit. Myc. Soc, vol. iv, 1914, pp. 247-248) who germinated the 

 spores of the Coprinus on sterilised blocks of Elm wood and observed that the 

 mycelium thus produced developed into typical tawny strands of the ozonium. 



