370 RESEARCHES ON FUNGI 



Sphaerobolus is, as a matter of fact, well adapted for spreading 

 from one substratum to an adjoining one, for it forms mycelial 

 strands as illustrated by Zopf in connexion with rabbit dung 

 (Fig. 166, p. 350). This mycelial mode of infection which involves 

 the agency of herbivorous animals, like the glebal mode of infection 

 described under (2), would account for the spread of the fungus 

 from one piece of wood to another far distant from it and for the 

 transportation of the fungus from one woodland area to another. 



(4) Infection of wood by spores or possibly gemmae which have 

 passed through the alimentary canal of some herbivorous animal. 

 After cows, horses, rabbits, etc., have swallowed one or more glebal 

 masses of Sphaerobolus and when these glebal masses are passing 

 down the alimentary canal, in all probability the fatty matrix of the 

 masses is soon destroyed by the action of lipase or some other enzyme, 

 with the result that the spores and gemmae are set free from the 

 prisons which have held them. The spores or gemmae or both may 

 therefore be extruded with the solid excrement of herbivorous animals 

 and be present in large numbers in fresh dung just deposited on the 

 ground. Now such fresh dung is much visited by dung-flies and 

 other insects. These insects, in walking, feeding, or laying eggs, 

 may either swallow some of the spores or gemmae or get their legs 

 or proboscides fouled with dung containing them. It is conceivable 

 that flies so contaminated may wing their way to sticks, logs, pieces 

 of worked wood, etc., and then deposit the spores or gemmae of 

 Sphaerobolus along with their excreta or with dung scraped off 

 their legs, wings, or bodies, and it is further conceivable that such 

 spores or gemmae might germinate subsequently and infect the mass 

 of wood lying beneath them. If insect transportation of the kind 

 just suggested actually takes place, it would account for the occur- 

 rence of Sphaerobolus on pieces of wood which, so far as one can 

 judge, could not have been infected by any of the means suggested 

 under (1), (2), or (3). At present, however, there are no experi- 

 mental facts supporting the idea of fly-dispersion except perhaps 

 one, namely, that according to both Pillay and Miss Walker, the 

 spores of Sphaerobolus can be caused to germinate by placing them 

 in a solution of pepsin. 1 



1 Vide supra, p. 293, 



