THE SPHAEROBOLUS GUN 287 



Sphaerobolus iowensis Walker 



"Unopened basidiocarps 1-1-5 mm. in diameter. Peridium 

 breaking stellately at the apex into 3-8 parts (usually 4-5), the tips 

 becoming only slightly recurved so that the peridium of the opened 

 fruit-body is somewhat cup-shaped. Interior of peridium cadmium- 

 yellow when first opened, glebal mass raw umber * when first ex- 

 posed, soon becoming almost black. Peridium separating into two 

 regions, an outer and an inner. Outer peridium during its develop- 

 ment and at maturity composed of two layers, an outer filamentous 

 and an inner pseudoparenchymatic. Inner region of a layer of 

 tangential hyphae and a palisade layer. Gleba containing during 

 its development many definite chambers lined with basidia. Wall 

 of glebal mass firm, composed of cells 6-15 \i in diameter. Contents 

 of glebal mass soft and gluey, never drying hard. Spores 5-6 x 

 6-10 fi (usually 5-6x8 /x)." 



Found on old coniferous boards at Hunters, Iowa, U.S.A. 

 Distinguished from S. stellatus by its chambered gleba and the 

 absence of a gelatinous layer in the peridium. 



The material for my own investigations on Sphaerobolus con- 

 sisted of : (1) fruit-bodies of 8. stellatus collected at Kenora in 

 western Ontario and at the Manitoba Agricultural College near 

 Winnipeg, and (2) cultures kindly sent to me by Dr. Leva Walker 

 from the University of Nebraska, U.S.A. 



Cultures. — Sphaerobolus can be readily cultivated on sterilised 

 wood or on horse dung (Fig. 142). One obtains fruit-bodies growing 

 on wood or dung, places them in a closed vessel in the laboratory, 

 and allows them to discharge their glebal masses against a sterilised 

 slide or glass plate. The projectiles stick to the surfaces which they 

 strike, and most of them, when shot out of the Sphaerobolus guns, 

 are free from contamination by bacteria. The projectiles caught 

 on a glass slide or plate are removed with a sterilised needle and 

 planted on sterilised agar plates. Each projectile sends out radially 

 a pure white mycelium with numerous clamp -connexions on the 



1 Vide Ridgway, Color Standards and Nomenclature. 



