452 University of California Pv-iUcatiorns in Botamy [Vol. 7 



hour after the sporophores are moistened, and continues for a maxi- 

 mum period of about two weeks. However, under natural conditions 

 the period is usually shorter, as the spores cease to fall as soon as the 

 sporophores become dry. Growth takes place, the most actively grow- 

 ing region being at the pileus margin and at the edge of each gill plate. 

 Specimens are naturally most commonly collected when in a dry 

 condition. 



The form of the fruit bodies varies greatly, depending in great 

 part upon the position of the surface of the substratum. Thus the 

 sporophores growing upon the under surface of a piece of wood are 

 quite different in form from those found upon the upper surface, and 

 those growing from a vertical surface differ from both of the preced- 

 ing ; but for every one of these three positions the form is fairly con- 

 stant. 



The diversity of form is due to the peculiar organization of the 

 sporophore, the stipe being attached to the upper surface of the pileus, 

 with the hymenophore upon the opposite side of the pileus away from 

 the stipe. Thus Schizophyllum differs from all other stipitate members 

 of the Agarieaeeae so far studied. This difference was conclusively 

 demonstrated by Hasselbring (1907), who grew the sporophores upon 

 a klinostat. He showed that, when not influenced by the force of 

 gravity, the stipe was always attached near the center of the pileus, 

 but on the opposite side from the ' ' gills. ' ' This unusual organization, 

 according to De Bary (1887), is also possessed by Cyphella, a member 

 of the Thellephoraeeae. 



The form which Hasselbring found is the one assumed by fruit 

 bodies growing in nature from the under surface of the substratum. 

 There is a stipe, which is usually short, attached to the center of the 

 upper surface of the pileus. The sporophore is shaped like a broad 

 funnel or bell, the hymenium lining the inner, and also the lower, sur- 

 face (fig. 1, pi. 52). On a vertical surface the form of the sporophores 

 depends in great part upon the length of the stipe (fig. 2, pi. 52). If 

 this structure is short, it is attached to the pileus near the edge, and 

 the sporophore is ear-shaped. If the stipe is long, it may be curved 

 downward at the outer end and be attached to the pileus near the 

 center, as in specimens grown upon an under surface. Then the shape 

 is that of a curved trumpet. In the ear-shaped forms the stipe is so 

 short that it cannot curve downward, so that the upper edge of the 

 young sporophore is stimulated by gravity (as shown by Hasselbring) 

 to grow more rapidly than the lower edge. Thus the hymenium is 



