2o6 RESEARCHES ON FUNGI 



The enlargement of the paraphyses from the size shown in 

 Fig. 87, A, to that shown in Fig. 87, B, takes place whilst the spores 

 are developing on their sterigmata and the gills are growing in length 

 and breadth (c/. Fig. 90, A-D). There can be no doubt that the 

 paraphyses, by increasing in size, are responsible for the stretching 

 of the hymenium as the pileus expands and the gills turn away from 

 the stipe, and they may therefore be thought of, in contradistinction 

 to the basidia, as the elastic elements of the hymenium. 



A cross-section of the hymenium corresponding to the surface 

 view of Fig. 87, A, is shown in Fig. 89 at A (p. 208). A study of 

 this section makes it evident that the long basidia, the short basidia, 

 and the paraphyses are all clearly differentiated from one another, 

 and further, that each of the basidia contains a single nucleus. 

 The nuclei have a diameter of about 8-5 yx and are so large that 

 they can be seen without difficulty in the living basidia mounted in 

 water or in dead basidia treated with iodine. To the subject of 

 nuclei we shall return later on. The basidium-bodies, when very 

 rudimentary, do not contain any glycogen but, when just about 

 to produce sterigmata, glycogen particles appear at their distal 

 ends, as may be proved by the red-brown reaction with iodine 

 (Fig. 89, A, g, p. 208). The glycogen particles appear in the long 

 basidia before they appear in the short basidia ; and this is one of 

 the signs that the former begin to mature sooner than the latter. 



The further development of the hymenium was followed by 

 studying cross-sections taken through the living gills. Since, in 

 a single gill, the basidia ripen their spores from below upwards, 

 it is impossible to determine the rate of hymenial development 

 by cutting sections of a single gill at higher and higher levels 

 of the barrel-shaped pileus at successive intervals of time. To 

 determine the rate of hymenial development and, at the same 

 time, to observe a series of successive developmental stages in the 

 hymenium, including the stage shown in Fig. 89, A, a series of 

 sections was therefore taken at successive intervals of time, not at 

 higher and higher levels from a single gill, but at the same level 

 from a series of gills, fresh and previously uninjured gills being used 

 for each successive observation. The details of the method employed 

 for these observations may be described as follows. A fruit-body 



