THE PSEUDORHIZA OF COPRINUS MACRORHIZUS 373 



characteristic pseuclorhiza. Since the beds had been left in utter 

 darkness from the time when they had been made up, it is clear 

 that light could have had nothing to do with the development of 

 the fruit-bodies. In particular, the direction of the growth of the 

 pseudorhiza could not have been influenced by a heliotropic stimulus. 

 Among the conclusions to which Weir ^ came in his already 

 mentioned investigations upon Coprinus macrorhizus was that this 

 fungus possesses " a positively geotropic, root-like sclerotium {ein 

 positiv-geotropisches, ivurze'dhnlirlies Sklerotium).''' This descrip- 

 tion of the pseudorhiza is entirely erroneous. The pseudorhiza, 

 as we have seen, grows upwards instead of downwards, its mode of 

 growth is intercalary and therefore not like that of a root, and 

 there is no ground to justify the view that it is to be regarded as a 

 sclerotium. A sclerotium is an independent more or less compact 

 mass of mycelium in which food materials are stored and which, 

 after resting for a longer or shorter time, gives rise to one or more 

 sporophores or to a new mycelium. But a pseudorhiza does not 

 consist of mycelium, for it is part of a sporophore ; nor is it a resting 

 body ; and the food materials which it contains are not. reserve 

 food materials but materials in transit to the developing pileus and 

 stipe-shaft. 



1 Weir, lor. cit., p. 319. 



