THE SPHAEROBOLUS GUN 361 



Phycomycetes and the Basidiomycetes, respectively, there are no 

 other guns to compare in violence with those of Pilobolus and 

 Sphaerobolus ; while, in the Discomycetes, Ascobolus immersus 

 shoots its spore-masses higher and farther horizontally than any 

 Peziza or other species shoots its isolated wind-dispersed spores. 

 (3) Adhesiveness of the Projectile. The Pilobolus, Ascobolus 



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Fig. 172. — Diagram illustrating the fruit-bodies of three copro- 

 philous fungi, similarly adapted for the dispersion of their 

 spores, one from each of the three great fungus subdivisions : 

 a, Pilobolus longipes (Phycomycetes) ; b, Ascobolus immersus 

 (Ascomycetes) ; and c, Sphaerobolus stellatus (Basidiomycetes). 

 The long arrows indicate the direction of the light and the short 

 arrows the direction in which the projectiles are shot. The 

 projectiles are shown between the two sets of arrows. The 

 fungus gun of the Pilobolus is a sporangiophore and the pro- 

 jectile a sporangium to which a drop of cell-sap is attached. 

 The gun of the Ascobolus is an ascus and the projectile is a 

 group of eight ascospores clinging together and enveloped by a 

 drop of cell-sap. The gun of the Sphaerobolus is a peridium 

 with an everting inner layer (shown everted), and the projectile 

 is a gleba surrounded by a thin coat of liquid. All the guns 

 are heliotropic and all shoot away a massive projectile, con- 

 taining many spores, on to herbage. 



immersus, and Sphaerobolus projectiles are all remarkably glutinous, 

 so that they adhere to herbage or to anything else that they may 

 strike or fall upon after they have been shot from their guns, and so 

 that, after drying, they cannot be dislodged by the wind. 



The adhesive matter of the projectile of Pilobolus consists of a 

 thick ring of jelly which is produced inside the sporangium and 

 becomes exposed to the air by the dehiscence of the sporangial wall ; 

 that of Ascobolus immersus consists of eight very thick gelatinous 

 outer spore- walls, which are fused together ; while that of Sphaero- 



