8 RESEARCHES ON FUNGI 



cornea the spores develop and are discharged with hitherto unsus- 

 pected rapidity, (2) that the excretion of a water-drop precedes 

 violent spore-discharge, (3) that there is no drop left on the 

 sterigma after discharge, and (4) that a newly-developed sterigma 

 collapses a few minutes after discharging a single spore and, there- 

 fore, that a sterigma does not produce any more spores than one. 



A spore of Calocera cornea, when coming into existence, arises 

 obliquely and not directly at the end of the sterigma, as may be 

 seen in Fig. 2 at C. The result of this is that a hilum is formed 

 which projects toward the axis of the basidium-body. The excretion 

 of the drop of water always takes place from the hilum. It there- 

 fore seems probable that the hilum is morphologically and physio- 

 logically of considerable importance. It is evidently a structure 

 which is specialised for the rapid excretion of water, and it doubtless 

 plays a very important role in bringing about spore-discharge. 



In different species of Hymenomycetes, the interval of time 

 between the moment when a spore begins to develop on the end 

 of the sterigma and the moment of discharge is by no means 

 constant, as will be shown by data given in the next Chapter. 

 For the present it is sufficient to remark that this interval, whilst 

 very short for Calocera cornea, is still shorter for certain other 

 Hymenomycetes. Indeed, in some species, e.g. Collybia velutipes and 

 Dacryomyces deliquescens, it is reduced to even less than one hour. 



The Water-drop. The excretion of a water-drop just before 

 spore- discharge occurs not only in Calocera cornea but in numerous 

 other, and probably in all, species of Hymenomycetes. Among 

 some fifty species in which I have observed it may be mentioned 

 those given in the Table on the opposite page. 



The species in this list are fairly representative of the 

 Hymenomycetes in general. They are sufficient to show that drop- 

 excretion before spore-discharge is the rule in this great group. 



With the high power of the microscope (magnification usually 

 440) I have watched hundreds of spores leave their sterigmata in 

 different species, and never once, since I became acquainted with 

 the excretory process, have I watched for the preliminary water- 

 drop in vain. 



In order to observe individual spores leaving their sterigmata 



