76 RESEARCHES ON FUNGI 



the stipe is likely to be subjected. The flesh of the pileus is also 

 very thin and, in the saving of substance thus effected, we are 

 reminded once more of other ephemeral fruit-bodies, namely, those 

 of Coprini, Psaihyrella disseminata, and Lepiota cepaestipes. The 

 splitting of the gills from above downwards in the outer part of 

 the pileus takes place just as in Coprinus lagopus, Psaihyrella dis- 

 seminata, etc., and is a rapid and very simple means of opening out 

 the pileus without any corresponding growth of the pileus-flesh. 

 The gelatinous pellicle, which covers the entire surface of the 

 pileus before the fruit-body expands, fails to extend as the pileus 

 opens, with the result that the outer part of the pileus, which in the 

 extended condition becomes exceedingly thin and delicate, is unable 

 to resist for long any drying breeze to which it may be exposed. 

 The gills are not stiff and tough, but are very watery. The hy- 

 menium is so organised that all the basidia can shed their spores in 

 the short period of time during which the pileus is expanded. The 

 basidia, relatively to the paraphyses, occupy a smaller proportion 

 of the hymenium than they do in Psalliota campestris and other 

 members of the Panaeolus Sub-type, where the spore-discharge 

 period is a long one. The number of basidia to come to maturity 

 on any unit area of the hymenium is therefore reduced in correlation 

 with the ephemeral existence of the pileus. Where the elements 

 of the hymenium are arranged in a very regular pattern, as some- 

 times happens, it can be observed that the number of generations 

 of basidia is four only — a number corresponding to that of the 

 ephemeral fruit-bodies described in connection with the Psathyrella 

 Sub-type, but contrasting with that of the persistent Panaeolus 

 Sub -type where it is at least twice as great. The paraphyses are 

 relatively very large and are united into a system which forms a 

 ground-work or pavement containing and isolating the basidia, 

 just as in the Coprini, Psathyrella disseminata, and Lepiota cepae- 

 stipes. No doubt they serve to give mechanical strength to the 

 very watery gills as in the other fungi mentioned and, at the same 

 time, by their rapid increase in size, aid in the process of rapid 

 pileus-expansion when this takes place. A continuous system of 

 large paraphyses, such as we are discussing, contrasts with the 

 irregular strings of relatively small paraphyses such as we find in 



