PANAEOLUS CAMPANULATUS 



251 



a radially symmetrical man- 

 ner, the axis of the pileus 

 becomes perpendicular. The 

 bringing of the median planes 

 of the gills into exactly 

 vertical positions is accom- 

 plished by two adjustments, 

 a coarse and a fine. The 

 coarse adjustment consists of 

 the already mentioned nega- 

 tively geotropic movement of 

 the apex of the stipe which 

 brings all the median gill- 

 planes into approximately 

 vertical positions. The fine 

 adjustment, by which these 

 planes are brought precisely 

 into vertical positions, is 

 accomplished by the gills 

 themselves, for these become 

 positively geotropic and grow 

 downwards toward the earth's 

 centre. 1 



The Phenomenon of Mott- 

 ling. When the surface of 

 a gill of Panaeolus campanu- 



latus which is shedding Spores FlG - ^ Panaeolus campanulatus. Section 



of a fruit-body to show the mottling of 



is observed with the naked 

 eye, one can at once dis- 

 tinguish upon it a considerable 

 number of lighter and darker 

 areas which are so arranged 

 as to give the hymenium a 

 mottled appearance (Figs. 87 

 and 88). These areas, of 

 which the larger ones measure 1-2 mm. 

 1 Cf. vol. i, 1909, p. 49. 



the gills. In the dark areas of the gills, 

 the basidia bear black spores which are 

 ripe or nearly ripe. In the light areas the 

 basidia bear immature spores which are 

 either colourless or are only beginning to 

 turn brown. The base of the hollow stipe 

 is attached to a brown gelatinous layer of 

 mycelium. Grown in a pure horse-dung 

 culture from spores obtained from a fruit- 

 body of English origin. The pileus is ex- 

 panded more than is usual under natural 

 conditions (cf. Fig. 83). Natural size. 



across, are of very 



