342 RESEARCHES ON FUNGI 



During the time that a basidium is discharging its spores, the 

 basidium-body and the sterigmata do not appear to undergo any 

 alteration. The basidium-body, before, during, and immediately 

 after spore-discharge, owing to the convexity of its top, appears 

 light in the centre and dark at the periphery. I watched several 

 basidia shed all their spores, and continued to watch them for some 

 time after the last spore of each had disappeared, in order to become 

 acquainted with the phenomenon of their collapse. It was found 

 that, until about twenty minutes after the last spore has been shot 

 away, a basidium remains prominent and apparently unaltered, 

 but that at the end of this time it undergoes a rapid change. In 

 the course of about one more minute, its sterigmata are drawn 

 together and the end of the basidium-body becomes darkened 

 and relatively difficult to observe. There can be no doubt that 

 during this minute the basidium collapses : the end of the basidium- 

 body becomes concave, the sterigmata are drawn down into the 

 concavity so formed, and at the same time the basidium sinks so 

 that its end is no longer protuberant beyond the general level of 

 the hymenium marked by the exterior of the paraphyses. For 

 four different basidia the actual moment at which the process of 

 collapse began after the discharge of the last spore was observed 

 to be 23, 16, 16, and 20 minutes respectively, or, upon the average, 

 about 19 minutes. 



The actual moment of the collapse of the basidia of any one 

 generation precedes only by a few minutes the beginning of the 

 development of the spores on the sterigmata of the basidia of the 

 succeeding generation. If, owing to any miscarriage of develop- 

 ment, the spores of a basidium do not happen to be discharged when 

 they should be under normal conditions, the basidium collapses 

 apparently at the normal time, i.e. at the time at which it would 

 have collapsed if it had discharged its spores. It is obvious, there- 

 fore, that basidial collapse takes place just sufficiently soon to 

 secure that any undischarged spores of one generation shall be 

 dragged down to the general level of the hymenium before the 

 already protuberant basidia of the succeeding generation begin to 

 develop their spores. The undischarged spores of one generation 

 are moved by basidial collapse from their place of origin to their 



