THE SPHAEROBOLUS GUN 



365 



sporous projectiles, and of (2) herbivorous animals, which swallow 

 the projectiles, disperse the spores in the contents of their alimentary 

 canals, and deposit the spores in their excreta at various places in 

 pastures. 



Sphaerobolus as a Member of the More Specialised of Two Groups 

 of Coprophilous Fungi. — So far as the arrangements for securing the 

 dissemination of the spores are concerned, coprophilous fungi may be 

 divided into two groups : (1) a more primitive group which succes- 

 sively makes use of three external agents — the wind, flowering plants, 

 and herbivorous animals — and (2) a more highly specialised group 

 which dispenses with the wind and which successively makes use of 

 only two external agents — flowering plants and herbivorous animals. 

 Sphaerobolus belongs to the more specialised group. Examples of 

 fungi belonging to each of the two groups are given in the accom- 

 panying Table. 



Coprophilous Fungi 



The fungi of Group I shoot away their ascospores, basidiospores, 

 etc., singly and to a relatively short distance — a distance just 

 sufficient to enable the wind to envelop the spores and carry them 



1 Galera bulbifera is a species described by C. H. Kauffman (The Agaricaceae of 

 Michigan, Lansing, Mich., U.S.A., Vol. I, 1918, p. 496) and is known by its bulbous 

 base. It occurs commonly on old horse dung in central Canada and has often 

 come up on that substratum in my laboratory. 



2 I have not yet investigated Thelebolus stercoreus. However, Brefeld (Unter- 

 suchungen iiber Pike, Minister i. W., Heft IX, 1891, p. 114) states that its great 

 spore-mass is shot with much force on to the cover of the culture dish. It is therefore 

 clear that the projectile of T. stercoreus resembles the projectiles of the other fungi 

 of Group II. 



