358 RESEARCHES ON FUNGI 



How did Sphaerobolus stellatus come to invade the cow-dung 

 plats in the first instance ? It is most unlikely that glebal masses 

 should have been shot on to the plats from fruit-bodies growing on 

 stumps of trees, etc. ; for (1) the plats were lying out in the open at a 

 considerable distance from the nearest woods, and (2) in those woods, 

 neither before nor since November 14, 1923, have any fruit-bodies 

 of Sphaerobolus ever been found. It is also most unlikely that the 

 wind should have blown to the plats either glebal masses as wholes 

 or individual spores or gemmae ; for (1) a glebal mass is so adhesive 

 that it cannot be dislodged from its substratum even during a gale, 

 and (2) the spores and gemmae cannot escape from a glebal mass 

 attached to grass, etc., because they are embedded in a glutinous 

 matrix which resists disintegration by wind and rain. 1 The simplest 

 and most satisfactory answer to our question seems to be as follows : 

 the cows (Fig. 171) some months previously to November 14 had 

 eaten herbage like that which I found around the two cow-dung 

 plats as already described, i.e. herbage to which glebal masses were 

 attached ; the spores or gemmae, or both, had passed unharmed 

 down the alimentary canals of the cows concerned and had been 

 extruded in the faeces, where they germinated ; subsequently, after 

 the dung-plats had become much altered and largely exhausted by 

 other fungi and by insects, the mycelium derived from the Sphaero- 

 bolus spores or gemmae, or both, grew freely in the core of the dung 

 plats and eventually produced fruit-bodies at the dung-plats' 

 surface. 



In all probability, whenever Sphaerobolus is found on the solid 

 excreta of herbivorous animals, the infection of the substratum, in 

 the first place, has been due to the animals concerned having swal- 

 lowed one or more glebal masses along with herbage to which the 

 masses were attached. 



From a consideration of : (1) the general structure and the 



of the mycelium. In the first half of November up to the 16th, 1931, we again found 

 8. stellatus in a pasture at the Agricultural College. It was present on many cow- 

 dung plats, on one mass of horse dung, and on a soft-wood board and a piece of 

 packing-case cardboard which had been thrown down near an infected cow-dung 

 plat. Again, a number of glebae were found which had been discharged from 

 fruit-bodies developed on dung and which had stuck to surrounding grass-blades, etc. 

 1 Vide supra, p. 297. 



