140 RESEARCHES ON FUNGI 



maturity, in the collar formed by the inner ends of the gills around 

 the top of the stipe, and in the black colour, almost identical size, 

 and shape of the spores. However, the Winnipeg species differs 

 from Coprinus plicatilis : in (1) having a somewhat browner pileus 

 in the expanded condition, in (2) having a somewhat longer stipe 

 relatively to the breadth of the pileus, in (3) growing on horse dung 

 instead of on grassy turf, but especially in (4) the fact that the 

 lower portion of the vertical part of each gill undergoes a slight 

 but quite definite amount of autodigestion from below upwards 

 during the period of spore-discharge. The Winnipeg species, which 

 seems to be new and as yet undescribed, is evidently a Coprinus and 

 serves to connect Coprinus plicatilis with the more typical Coprini, 

 such as Coprinus lagopus, C. niveus, and others, in which auto- 

 digestion of the gills from below upwards is a very obvious and 

 striking character. 



Falck's Theory of Radiosensitivity in Coprinus. — Richard 

 Falck,^ as a result of experiments made with the aid of a lamp, etc., 

 has come to the conclusion that Helvella, Morchella, Gyromitra, 

 and some other Discomycetes in which the hymenium is dark- 

 coloured are radiosensitive in respect to the discharge of the spores 

 from their asci, i.e. that the fruit-bodies discharge their ripe spores 

 only when their temperature is raised above a certain minimum by 

 heat radiated to them by the sun or some other external heat-source. 

 He thinks that, under natural conditions in the spring, species of 

 Morchella, etc., "shed their spores only in direct sunlight, from 

 sometime in the morning until sometime in the afternoon when the 

 sun has passed its highest point and the period of greatest warming 

 is over." ^ Falck has undoubtedly shown that radiant heat has a 

 remarkable action upon the ripe asci of certain Helvellaceae in that 

 it stimulates them to explode and shoot away their spores ; but, 

 when he attempts to extend his theory of radiosensitivity to the 

 Basidiomycetes and, in particular, to the Coprini, I am unable to 

 follow him. 



Under the heading " Arrangements for using the radiation from 



1 Richard Falck, Mycologische Untersuchungen und Berichte, Jena, Heft II, 

 1916, pp. 77-144, Taf. I and II. 



2 Ibid., p. 125. 



