SPORE-DISCHARGE IN THE TREMELLINEAE 161 



the average time taken for the development and ripening of an 

 individual spore, from the moment that the spore appears on the 

 sterigma as a tiny rudiment until the moment of discharge, was 

 observed to be : for Calocera cornea 1 hour and 20 minutes, for 

 Exidia albida 1 hour and 15 minutes, and for Dacryomyces deliquescens 

 50 minutes. 1 These rapid rates of spore-development correspond 

 to similar rapid rates for Marasmius oreades and Collybia dryo- 

 phila, and appear to be correlated with the dependence of the 

 fruit-bodies for their activity upon moist conditions. Rapid 

 spore-development enables a dried fruit-body to resume its spore- 

 producing function very quickly after the advent of rain. 



In Chapter II, I showed by comparative observations that, 

 on the whole, spores with walls which are warted or which are 

 thick and pigmented take considerably longer to develop than 

 spores with walls which are smooth and thin and colourless. Now 

 the spores of the Tremellineae are all smooth and thin and colour- 

 less. There can be little doubt, therefore, that the simplicity of 

 the spore-wall in this group is correlated with rapid spore- 

 development. 



We may connect up the ideas developed above as follows. 

 The Tremellineae are lignicolous and therefore subjected to 

 temporary periods of drought. They are therefore organised 

 so as to retain their vitality when dry, and so as to resume their 

 former shape and revive rapidly on the advent of rain. This 

 organisation involves the production of a gelatinous matrix for 

 absorbing and storing water rapidly and also involves the existence 

 of basidia which ripen their spores in a minimum amount of time. 

 The rapid ripening of the spores is favoured by the simplicity of 

 the spore-walls, these being smooth and thin and colourless. 



The forms of the fruit-bodies of the Tremellineae are very 

 various. The most gelatinous fruit-bodies, e.g. those in the genera 

 Dacryomyces, Tremella, and Ulocolla, consist of more or less spherical 

 or hemispherical lumps which are either coarsely lobate or cere- 

 briform at the surface (Fig. 56). In these, the hymenium covers 

 the whole of the exterior surface. Part of, or the whole of, the 

 hymenium, therefore, often looks upwards a very exceptional 

 1 Vide supra, Chapter II. 



