SPORE DISCHARGE AND DISSEMINATION 



347 



Discharge of peridioles. The discharge of the peridiole (gleba-con- 

 taining basidiospores) of Sphaerobolus depends largely upon the unique 

 structure of the fruit body (Fig. 71). The spherical fruit body measures 

 but 2 to 3 mm. in diameter. The peridium is made up of six distinct 

 layers. At maturity, the peridium breaks open at the top, in a stellate 

 manner, through all but the sixth, or innermost, layer, which surrounds 



Fig. 71. Structure of fruit body and mechanism of discharge of peridiole of Sphaero- 

 bolus stellatus. A, section of mature sporocarp, with six layers (1-6) that invest the 

 central peridiole (7). B, dehiscence of sporocarp at apex. The inner membrane is 

 liquefied. C, eversion of the remaining two layers by which the peridiole, D, is sud- 

 denly discharged. (Reproduced by permission from Wolf and Wolf, The Fungi, Vol. 

 II, p. 203, John Wiley & Sons, Inc., New York, 1947.) 



the peridiole. This layer deliquesces, and the peridiole then rests in the 

 watery substance produced. A split then occurs between layers 3 and 4, 

 beginning at the base but not progressing to the very top. Laj^er 4, the 

 fibrous layer, is composed of small, rather closely packed cells, while layer 

 5, the palisade layer, is made up of comparatively large, somewhat 

 elongated cells. The cells of the palisade, which is on the concave sur- 

 face, increase in turgor and in size and are held under great tension by 

 the relatively inelastic fibrous layer. These inner layers are suddenly 

 everted, acting as a catapult, throwing the peridiole violently upward. 

 Walker (1927) has reported that the peridiole of S. stellatus may be 

 thrown to a vertical distance of 14 ft., while Buller (1934) reports a maxi- 

 mum horizontal distance of 18 ft. 7 in. 



