444 RESEARCHES ON FUNGI 



Camera-lucida Studies of a Nearly Exhausted Hymenium. The 

 studies of the hymenium represented in Fig. 151 were made upon 

 an old and nearly exhausted mushroom obtained from a field in 

 England. The top of the mushroom was flat, and the gills were 

 of a dark reddish-brown colour, indeed almost black ; but the 

 mottling of the hymenial surface could still be discerned. Evidently 

 the fruit-body had been shedding spores for some days and was 

 nearing the point of exhaustion. Sections of the living gills were 

 made with a hand-razor as before, and two of them are shown at 

 A and B in Fig. 151. 



In Fig. 151, A, the elements nos. 1, 2, and 3 are present-genera- 

 tion basidia from all of which the spores were knocked off in cutting 

 the section as at no. 3 ; but in nos. 1 and 2 the spores have been 

 restored semi-diagrammatically. No. 4 is an old past-generation 

 basidium arising deep down in the subhymenium from the cell 

 no. VIII. The outlines of the other past-generations basidia 

 cannot be clearly discerned, but it is evident that their gelatinised 

 tops make up the general level of the hymenium which can be seen 

 at /. There are no coming-generation basidia included in the 

 section. Elements nos. 5, 6, and 7 are paraphyses. Two waste 

 spores, w, are lying on the hymenium. The subhymenium consists 

 roughly of three layers of cells : I to IV inclusive, V to VII 

 inclusive, and VIII to X inclusive. It is evident that the past- 

 generations basidia have all disappeared from the section except 

 no. 4 ; otherwise it would be possible to observe their outlines 

 and their attachments to the cells of the two upper layers of the 

 subhymenium. 



In Fig. 151, B, the elements nos. 1 and 2 are present-generation 

 basidia from which the spores were knocked off in cutting the 

 section ; but for no. 2 the spores have been restored semi- 

 diagrammatically. Nos. 3 and 4 are coming-generation basidia, 

 the presence of which indicates that the mushroom, although old, 

 would continue to discharge spores for at least half a day and 

 possibly for twenty-four hours longer. The past-generations 

 basidia which can be clearly distinguished are elements nos. 5, 

 6, 7, 8, and 9. The tops of other past-generations basidia, the 

 walls of which have apparently been gelatinised, make up the 



