CHAPTER II 



THE DISPERSAL OF THE SPORES OF ASCOMYCETES BY HERBIVOR- 

 OUS ANIMALS ILLUSTRATED BY AN ACCOUNT OF ASCOBOLUS 

 IMMEItSUSPILOBO'LUS, EMPUSA MUSGJE LYCOPERDON THE 

 SOUND PRODUCED BY THE DISCHARGE OF SPORES, WITH 

 SPECIAL REFERENCE TO PILOBOLUS. 



The Dispersal of the Spores of Ascomycetes by Herbivorous 

 Animals, illustrated by an Account of Ascobolus immersus. 

 Pilobolus, Empusa muscw. Ascomycetes in which the spores after 

 ejection from the asci are dispersed by herbivorous animals develop 

 on faeces and have a coprophilous mode of existence. Of these the 

 most striking examples are afforded by species of Ascobolus, e.g. 

 A. immersus, and by Saccobolus. Their spores are arranged in the 

 ascus more or less in two rows, and are held firmly together in 

 Ascobolus by their gelatinous coats (Fig. 81), and in Saccobolus by 

 a special investing membrane. The object, so to speak, of spore- 

 discharge in these fungi is to eject the spores from the ascus to as 

 great a distance as possible, so that they may fall at once on to the 

 surrounding grass. In feeding, herbivorous animals swallow the 

 grass and spores together. The latter pass out in the excrement 

 uninjured and ready to germinate. In their mode of spore-dispersal 

 these Ascomycetes exactly resemble Pilobolus. The attachment of 

 the eight spores to one another, so as to form an oval mass, prevents 

 the ascus jet being broken up by surface tension and thus keeps 

 the mass of the projectile constant. This enables the spores to be 

 thrown to a greater distance from the faecal substratum than would 

 otherwise be possible. 



For the sake of comparison with the Hymenomycetes, a special 

 investigation was made upon the spore-discharge of Ascobolus 

 immersus, the asci and spores of which are of large size even for an 

 Ascobolus. The fungus made its appearance on a horse-dung culture 



