THE SPHAEROBOLUS GUN 355 



pieces, the mycelium in a plat was often limited, except for extensions 

 to the periphery here and there, to a larger or smaller inner core, 

 the mass of dung occupied by the mycelium being readily distin- 

 guishable from the surrounding unoccupied mass of dung by its 

 whiteness. The fruit-bodies on the exterior of a dung plat usually 

 occurred in rows, each row situated in a crevice between two suc- 

 cessive droppings, i.e. in a place where the mycelium had reached 

 the light and had received the stimulus necessary for fruit-body 

 formation. Fig. 167 shows one of the cow-dung plats seen from 

 above. It was found to contain the mycelium of Sphaerobolus stellatus 

 and also a number of rudimentary fruit-bodies concealed in the 

 exterior crevices between the different layers. Fig. 168 shows a 

 similar dung plat broken open, with the characteristic mycelium of 

 S. stellatus in its interior. Fig. 169 shows an interior surface of 

 another dung plat. Here, the mycelium has extended to what was 

 a crevice between two layers of the dung and has formed there a 

 row of about twenty fruit-bodies (s). When this piece of dung was 

 set in a damp-chamber, the fruit-bodies completed their develop- 

 ment and discharged their glebal masses in the course of about a 

 week. 



Whenever pieces of the cow-dung plats infected with the myce- 

 lium of Sphaerobolus were kept moist in a glass vessel exposed to 

 daylight in a warm laboratory, within a week they produced an 

 abundant crop of fruit-bodies and soon a certain number of the 

 fruit-bodies opened each morning and discharged their glebal masses. 

 One such piece of cow dung bearing fruit-bodies is shown in Fig. 164 

 (p. 332). Fruit-bodies thus obtained provided me with material for 

 determining approximately the horizontal range of the Sphaerobolus 

 gun, and it was a fruit-body developed on cow dung which shot its 

 projectile the record horizontal distance of 18 feet 7 inches. 1 



The glebal mass of Sphaerobolus resembles the sporangium of 

 Pilobolus in that it is very adhesive and, after being discharged, 

 sticks to anything which it may happen to strike. Bearing this in 

 mind, I examined the phanerogamic vegetation surrounding two 

 of the Sphaerobolus dung plats and had the satisfaction of finding 

 many glebal masses which had been shot on to it. Within a few 



1 Vide supra, p. 334. 



