CHAPTER XIV 



THE NOCTURNAL SPORE-DISCHARGE OF PLEUROTUS OSTRE- 

 ATUS AND COLLYBIA VELUTIPES AS OBSERVED WITH 

 AN ELECTRIC HAND-LAMP 



The Electric Hand-lanip and its Eimi>lo}'nieiit in the Field — Pleiirotiis ostreatiis — 

 The Effects of High and Low Temperatures — November and December Field- 

 observations — Collybia velutipes and its Activity in Mid-winter 



The Electric Hand-lamp and its Employment in the Field. ^In 

 Volume I. of these Researches I described a beam-of-light method 

 for rendering visible the spores falhng from a hymenomycetous 

 fruit-body in the laboratory. ^ It was shown that, if one suspends 

 such a fruit- body in a closed beaker and directs a strong beam of 

 light through the air below the pileus, then, with the naked eye, one 

 can see the individual spores streaming away from the gills. The 

 existence of the spore-stream, thus revealed, affords striking evidence 

 of the intense activity with which a fruit-body carries out its one 

 great function of producing and liberating spores ; and, when once 

 such a spore-stream has been seen, it is not likely to be forgotten. 

 Recently, for the purpose of observing the discharge of spores 

 from fruit-bodies growing in the open under natural conditions, 

 I have employed a modification of the beam-of-light method ; and 

 the essential conditions for using this modified method with success 

 will now be set forth : 



(1) One must first find some fruit-bodies shedding spores. 

 Particularly convenient for observation are hgnicolous fungi, such 

 as Pleurotus ostreatus and Collybia velutipes, when found growing on 

 the side of a tree-trunk a few feet above the ground and therefore 

 well within reach. 



^ These Researches, vol. i, 1909, pp. 94-101. 



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