STROPHARIA SEMIGLOBATA 339 



object for study. There was a minute crack in the cover-glass, 

 and it was found necessary to renew the water in the cell once 

 during the investigation. A small portion of a dark area, from 

 which the spores were being discharged, was chosen for special 

 study ; and in the course of eight hours' continuous watching by 

 myself and by my nephew, Mr. Bernard Workman, to whom I am 

 much indebted for timely assistance, I succeeded in observing the 

 following : (1) the last phase of one generation of basidia, including 

 the discharge of the spores and the collapse of the basidium-bodies ; 

 (2) the development and discharge of the spores of a second genera- 

 tion of basidia, followed by the collapse of the basidium-bodies ; 

 and (3) the development of spores on the sterigmata of a third 

 generation of basidia. The horizontal-microscope method, which 

 was employed in a similar investigation for Panaeolus campanu- 

 latus, 1 has various advantages over the just-described vertical- 

 microscope method, for it permits one to observe a gill which is 

 attached to a fruit-body in such a way that the spores discharged 

 from it are shot clear of the hymenium, and it permits of the obser- 

 vations being carried on for several days instead of for a portion of 

 one. Nevertheless, the vertical-microscope method employed in the 

 present investigation sufficed me to attain the end in view. Its 

 disadvantages are that the gill has to be removed from the fruit- 

 body and therefore will not continue to develop normally for many 

 hours, and also that the spores which are shot upwards must neces- 

 sarily fall back again on to the hymenium where their accumulation 

 tends to hinder one from seeing the hy menial elements clearly. Its 

 chief advantage lies in its simplicity, the only apparatus involved 

 being an ordinary microscope and a compressor cell. 



The developmental waves, which have already been described 

 as passing through the hymenium, were actually observed in their 

 progress. In the centre of the field of the microscope was an area 

 which was at first dark, and waves of development travelled out 

 from it radially, somewhat in the way represented in Fig. 116 

 (p. 332). The passage of a single undulation across the field of the 

 microscope occupied several hours. 



Close attention to the small area specially chosen for minute 

 1 Chap. X, pp. 260-264. 



