402 



RESEARCHES ON FUNGI 



during the expansion of the pileus was therefore taking place 

 without any spores being wasted by lodging on the gill-sides. 



The gills, when spore-discharge began, were pinkish, but by 

 the second day were brown. The brown rapidly deepened 

 so that the gills became almost black. The darkening of the 

 ^^^^^^^^^^^^^^^^^^^^^^^^^^ gills, as has al- 

 ready been pointed 

 out, is simply due 

 to the deepening of 

 the pigmented cell- 

 sap in the cells of 

 the gills and is not 

 due to decay or, 

 in the main, to the 

 accumulation of 

 waste spores. Even 

 when the gills had 

 become dark choco- 

 late - brown, the 

 hymenium still con- 

 tinued to liberate 

 vast numbers of 

 spores. 



The number of 

 spores which a 

 mushroom pro- 

 duces can be deter- 

 mined directly, by estimating the number of spores in the 

 spore-deposit (Fig. 141) or, indirectly, by estimating the number 

 of basidia which are formed in the hymenium. A spore-deposit, 

 which had been produced by a wild mushroom within forty-eight 

 hours from a pileus 8 cm. wide, was investigated with a counting 

 apparatus. The result was given in Volume I. 1 The number of 

 spores was found to be 1,800,000,000, from which it was concluded 

 that, on the average, about 40,000,000 had fallen during each hour 

 of the spore-fall period. However, since it has now been shown 

 1 Vol. i, 1909, p. 82. 



FIG. 141. A spore-deposit of a wild Mushroom, Psalliota 

 campestris, gathered at King's Heath, England. The 

 pileus was placed on white paper for about six hours. 

 To the right, the black spore -lines were formed 

 under interlamellar spaces, while the white spore- 

 free lines were left under the free gill-edges. To the 

 left, the clouding is due to the fact that the gills in 

 this region did not at first look vertically down- 

 wards. Natural size. 



