BASIDIA AND THE DISCHARGE OF SPORES 15 



fell upon one of the spores of the other basidium and stuck to it ; 

 whereupon I saw that a drop of water instantly ran from the 

 discharged spore toward the undischarged, and became held by 

 adhesion between the two (D). In a few seconds the drop spread 

 itself more widely over the spores, and then disappeared, doubtless 

 by evaporation. This observation leaves in my mind the con- 

 viction that the drop, which I had seen on the hilum before 

 discharge, had been carried by the spore during its flight. 



Observations similar in their nature to that just recorded 

 I have occasionally made when studying spore-discharge in other 

 species, e.g. Coprinus sterquilinus, Psalliota campeslris, and Oalera 

 tenera. In each of these a spore, after being shot upwards from 

 the horizontal hymenium, fell on to one of the basidia or paraphyses 

 and, at the moment of settling, was seen to have a drop of water 

 on its upper side. The drop in each case was approximately of 

 the same size as that which normally is excreted at the hilum. 

 In a few seconds it disappeared, partly by spreading slowly around 

 the spore and, doubtless, partly by evaporation. 



After making the occasional observations on the carriage of the 

 drop just described, I devised an experiment which, provided living 

 fruit-bodies are available, can be set up at any time and the results 

 of which are sufficient to prove that the hilum-drop is carried 

 by the spore in any hymenomycetous species whatsoever. The 

 arrangement of the apparatus and the mode of observation for 

 Nolanea pascua were as follows. 



A compressor cell, like that shown in the first illustration of 

 Chapter II, was used as a moist chamber to contain a piece of a 

 gill with a developing hymenium. 1 A very tiny drop of water was 

 placed on the base of the cell, and then a piece of a living gill dis- 

 sected from a just-gathered fruit-body of Nolanea pascua was laid 

 flat over the drop. The drop spread out into a fine film between 

 the under side of the piece of gill and the glass. The lid of the 

 compressor cell was then pushed down over the box until it was 

 nearer to the tops of the upward-projecting spores than 0-1 mm., 

 i.e. so that the under side of its cover-glass would form a target 



1 A similar compressor cell was used for various investigations recorded in 

 1909 in Volume I. Vide vol. i, Fig. 58, p. 167. 



