382 RESEARCHES ON FUNGI 



The outer non-everting set of membranes is of importance for the 

 working of the Sphaerobolus gun in that it holds fast the inner everting 

 set of membranes by its teeth as eversion takes place and so prevents the 

 inner set of membranes following after the projectile and interfering with 

 its flight. 



When discharge of the Sphaerobolus gun takes place, along with the 

 projectile there are shot away a few drops of slimy liquid derived from 

 the deliquescence of the peridial layer immediately surrounding the gleba. 



A projectile, on striking a hard object near the gun from which it has 

 been discharged, flattens out like a leaden bullet and becomes plano- 

 convex. 



The Sphaerobolus gun emits a distinct sound as it shoots away its 

 projectile. It is the largest, the most powerful, and the loudest of all 

 fungus guns. 



The maximum height and the maximum horizontal distance to which 

 projectiles of Sphaerobolus stellatus were expelled were : (1) for wild fruit- 

 bodies growing on a board, 7 feet 9 inches and 15 feet respectively ; and 

 (2) for wild fruit-bodies growing on cow dung, 7 feet and upwards (limit 

 not determined) and 18 feet 7 inches respectively. Miss Leva Walker, 

 who worked with a pure horse-dung culture of S. stellatus, observed that 

 the projectiles were shot to a maximum height of 14 feet 5 inches and to 

 a maximum horizontal distance of 17 feet 3 inches. 



The fruit-body of Sphaerobolus stellatus easily outranges any phanero- 

 gamic fruit of its own size. 



The kinetics of the Sphaerobolus gun have been investigated and the 

 following calculations have been made. 



If a projectile is shot 7 feet high, the projectile has an initial velocity 

 of upwards of 21 feet per second and takes upwards of 0-65 second to 

 reach its highest point. 



If a projectile is shot 14-5 feet high, the projectile has an initial 

 velocity of upwards of 30 feet per second and takes upwards of 0-95 

 second to reach its highest point. 



The time taken in the discharge of the gun is : (1) if the gun shoots 

 the projectile 7 feet high, about yoVe second ; and (2) if the gun shoots 

 the projectile 14-5 feet high, about y^T second. 



The momentum of a projectile shot 14-5 feet high, when leaving the 

 gun, is about 0-00008 inch. 



The kinetic energy of a projectile shot 14-5 feet high, when leaving 

 the gun, is about • 000037 foot pounds. 



The average force of the propelling peridium, when acting on the 

 projectile, is 0-13 poundals or 0-004 pounds. 



The rate of developing energy in a Sphaerobolus gun which shoots 

 a projectile 14-5 feet high is TTn V<7o horse power. 



Without a sufficient supply of water, the Sphaerobolus gun can 

 neither open stellately nor, if opened stel lately, discharge its projectile. 



