THE SPHAEROBOLUS GUN 



285 



opened fruit-body of typical S. stellatus is 1-5-2-0 mm. in diameter, 

 whereas that of its variety giganteus is 3-4 mm. in diameter. S. 

 iowensis differs from S. stellatus in the absence from its peridium of 

 an outer gelatinous 

 layer and in having 

 a distinctly cham- 

 bered gleba. The 

 typical form of 

 Sphaerobolus stellatus i 



may thus be des- 

 cribed : 



Sphaerobolus 

 stellatus Tode 1 



Basidiocarps 

 more or less deeply 

 embedded in the sur- 

 rounding arachnoid 

 mycelium and the 

 substratum ; when 

 young, spherical to 

 oval, 1-5-2-0 mm. 

 in diameter, whitish 

 or pale yellow owing 

 to the deep yellow 

 of the interior show- 

 ing faintly through 

 the fine white fila- 

 ments covering the 

 exterior, the outer 



layer of the peridium decidedly gelatinous; at maturity the peri- 

 dium splitting open above so as to form an urceolus in which 

 the glebal mass lies exposed to view, the rim of the urceolus 

 divided into some 6-8 acute stellately arranged teeth, the interior 

 surface of the urceolus down to the glebal mass orange-yellow. 

 1 I have drawn up this description from my own and Miss Walker's observations. 



Fig. 141. — Sphaerobolus iowensis. Vertical section of 

 a nearly mature fruit-body. The basidia have 

 now broken down and disappeared and the spore- 

 masses are held in place by tramal hyphae which 

 are now beginning to disintegrate and form a soft 

 gluey oily slime. The various layers of the 

 peridium can now be readily distinguished and, 

 centripetally, are : a layer of mycelium (lower 

 half), a layer of pseudoparenchyma, a fibrous 

 layer, a palisade layer passing into pseudo- 

 parenchyma above, and a thin pseudoparen- 

 chymatous layer completely surrounding the 

 gleba, i.e. the wall of the glebal mass. Section 

 prepared and photographed by Leva B. Walker. 

 Magnification, about 40. 



