i6o RESEARCHES ON FUNGI 



The gelatinous ring of a sporangium of Pilobolus Kleinii which 

 has dried up on a sheet of glass is so strongly attached by its lower 

 surface to the glass and by its upper surface to the lowest layer of 

 the spores which make up the spore-mass that, if one scrapes the 

 sporangium off the glass with a knife, the dried-up gelatinous ring 

 and the adherent lower halves of the walls of the lowest layer of 

 spores are left behind together in situ. The broken walls of the 

 spores are colourless and, in the mass, form a hexagonal pattern 

 reminding one of honey-comb. When a drop of water is added, 

 the jelly swells up and each hexagonal half-spore wall separates 

 from its neighbours and comes to have an oval outline. 



Under natural conditions in the open, Pilobolus Kleinii, P. 

 longipes, etc., grow in pastures on the dung-plats of horses, cows, 

 and other herbivorous animals, and the sporangia which their guns 

 shoot away strike and stick to the surface of leaves, stems, and 

 inflorescences of grasses and other plants making up the surround- 

 ing herbage (Fig. 80, p. 164) ; and the sporangia, on drying up, 

 become very firmly attached to their substrata, so firmly indeed 

 that the wind, however strongly it may blow, cannot dislodge 

 them. 



Sporangia which have dried up are also not easily dislodged from 

 their places of attachment by falling drops or moving films of water. 

 Evidence of this fact was obtained from some experiments which will 

 now be described. 



A plate of glass to which a number of sporangia were attached 

 was set obliquely under a tap in such a way that six of the sporangia 

 were struck by a rapid stream of large water drops which fell from 

 the nozzle of the tap for a distance of about one foot. All of the 

 six sporangia withstood the hammering of the drops unmoved for 

 half an hour. Then one of them was washed away. The other 

 five were washed away in the course of the next two and a half hours. 

 A number of other sporangia which were on the plate and were 

 washed by the stream of water running down the plate for three 

 hours were, at the end of this time, still attached to the plate in 

 their original positions. 



In another experiment, a postage stamp was stuck on a glass 

 plate to which some sporangia were already attached and, as before, 



