202 RESEARCHES ON FUNGI 



from without correspond, therefore, not to spaces between adjacent 

 gills, but to spaces between half gills pulled asunder. 



During autodigestion, the oblique free edge of each gill is black 

 and covered with a liquid film. From this edge evaporation takes 

 place and no actual drops of inky fluid form upon it. The spaces 

 between the gills, therefore, do not become choked up, but remain 

 open just as in a Mushroom (Plate IV., Fig. 23). As autodigestion 

 proceeds, each gill, when seen in face view, gets narrower and 

 narrower below, until it is almost reduced to nothing (Plate II.. 

 Fig. 8). The membranous flesh of the pileus bearing the remains 

 of the gills often curls outwards and upwards so as to form a neat 

 and curious circular roll (Plate IV., Figs. 22 and 24; Plate III, 

 Fig». 9 and 10). Sometimes, however, it simply hangs downwards, 

 in which case the pileus looks ragged and untidy (Plate II., Fig. 8: 

 Plate IV., Fig. 21). With the continuance of autodigestion, the 

 now useless material just described is gradually converted more or 

 less completely into drops of inky-looking fluid, which may often 

 be seen hanging from the rim of the pileus (Plate II., Fig. 10 : 

 Plate IV., Fig. 24). It will shortly become clear that the formation 

 of the circular roll on the top of the pileus is to be regarded as 

 an admirable method of securing that that part of the pileus which 

 has ceased to have any functional significance shall be as far 

 removed as possible from the paths of the falling spores, and thus 

 prevented from hindering spore-disposal by the wind. 



If one allows an upright fruit-body, with its stipe placed in wet 

 sand, to shed its spores under a bell-jar, one finds by microscopic 

 examination that the inky drops, produced by autodigestion, consist 

 of a brown fluid containing granules but practically free from spores. 

 The fluid, therefore, is not made black by spores. The colour is 

 probably due to an oxydase which unites the oxygen of the air 

 with some substance liberated from the dying cells, for it was 

 found that the colourless juice squeezed from an unripe pileus 

 turns brown in a few hours. 1 The drops collect only on the rim of 

 the pileus, where they do not interfere with the liberation of the 

 spores into the air. If paper is placed round the base of the stipe, 



1 Cf. A. H. R. BiUler, "The Enzymes of Polyporus squamosus" Ami. of Bot. y 

 vol. xx. p. 51. 



