BASIDIOMYCETES 417 



be shot out over the rim of the cup, and consequently would remain in 

 its interior. Inversely, this small range has enabled the Basidiomycetes 

 to develop the hymenophore into lamellae and tubes. If the explosive 

 mechanism were as powerful as in the Discomycetes, the spores would 

 be discharged upon the opposite lamella and would remain hanging there. 

 The weak force in the Basidiomycetes just suffices to separate the spores 

 from the hymenium and to permit free fall from the spaces between 

 vertically placed hymenia to the open air. 



The basidia depend upon wind dispersal of spores. This goes so far 

 that, e.g., in germination of teliospores, under water they either abort or 

 grow so long that they may discharge their spores above it. With the 

 progressive development of fructification from gymnocarpous to angio- 

 carpous forms, this wind dispersal becomes decreasingly effective. The 

 hymenia lie in the interior of the fructification and, until the maturity of 

 the basidia, remain surrounded by layers of tissues. Just as in the Tuber- 

 aceae, the ascus ceases to be an apparatus for the discharge of spores, but 

 is a round structure possessing a soft, flaccid wall without cover, so in 

 the basidia the ability to discharge spores is suppressed, the sterigmata 

 degenerate, the spores appear sessile and their dissemination is entirely 

 passive, either by wind (e.g., Lycoperdon), by insects (e.g., Phallaceae) or 

 by rodents (e.g., Hymenogasteraceae). In the Phallaceae, the mature 

 hymenia are imbedded in a slimy, sweetish mass which sends out a power- 

 ful odor perceptible by man at a distance; the spores are enclosed in this 

 slime during their whole life, and fall with it to the ground or cling to the 

 insects eating it. Thus the original organization of the basidium as an 

 apparatus of discharge has only a historical significance : in the transition 

 from wind dispersal to insect dispersal the basidia have lost their biolog- 

 ical value. Similarly in many of the Hymenogasteraceae and Hysteran- 

 giaceae, the fructifications possess a strong odor which attracts rodents 

 to them. In some places they form the chief food supply of the rodents 

 for several months of the year, and their spores are disseminated with 

 the excrement of the animals. 



The basidiospores are entirely unicellular, in the lower forms hyaline, 

 thin walled, ephemeral, in the higher forms colored, thick walled, some- 

 times having a germ pore, mostly resting spores very resistant to external 

 influences. In the forms with ephemeral basidiospores, the function of 

 the biological protection is generally assumed by the sclerobasidia. In 

 their totality as spore dust, they possess a very constant and character- 

 istic color for each species, but these colors probably are of no significance 

 in determining relationships. It appears much more probable that, in 

 the different series, a development of color from light to dark has taken 

 place in which yellow is more primitive than red and red more primitive 

 than blue. 



