298 RESEARCHES ON FUNGI 



The presence of bacteria is not required for the germination of the 

 spores of Coprinus sterquilinus. 



The spores of Coprinus sterquilinus are able to germinate at a 

 temperature below 20° C. From eighty to ninety per cent, of the spores 

 germinated in a refrigerator in which the temperature varied from 5° 



to 10° C. 



The spores of Coprinus sterquilinus are able to germinate, without 

 having been dried or heated, immediately after they have been liberated 

 from a fruit-body. 



The struggle for possession of the substratum by mycelia derived 

 from spores embedded in dung-balls is discussed. 



In general, the spores of all Coprini germinate well in sterilised media 

 of various kinds and, therefore, in the complete absence of bacteria. 



Chapter V.— Attention is called to the mechanical problems involved 

 in the fixation of hymenomycetous fruit-bodies to their substratum. 



An analysis of the factors concerned in the mechanical fixation of 

 the fruit-body of Coprinus sterquilinus in horse-dung masses has been 

 attempted. 



The stipe of Coprinus sterquilinus becomes fixed in its faecal sub- 

 stratum only owing to a combination of various external and internal 

 factors for the fixation process. Light inhibits the development of all 

 the tiny rudiments of fruit-bodies which happen to arise on the illumi- 

 nated surface of the substratum, so that only those rudiments which 

 happen to develop in dark recesses beneath or between dung-balls can 

 possibly produce mature fruit-bodies. In the dark, a rudiment may 

 continue its development if this is not inhibited by the growth of a more 

 vigorous neighbouring rudiment. A favoured rudiment growing in the 

 dark at a short distance below the surface of the substratum devotes its 

 growth-energy to the development of a solid stout stipe-base, while the 

 pileus which caps it remains small and conical, its development being 

 delayed. A negative geotropic stimulus soon causes the stipe-base to 

 push the rudimentary pileus upwards between the dung- balls or through 

 the dung-mass into the light ; and, as soon as the pileus has reached 

 the light and with this the free upper surface of the substratum, the 

 light inhibits the further growth in length of the stipe-base ; and then 

 the pileus and the hollow aerial stipe-shaft are developed to their full 

 length in succession. The structure of the dung-mass, which consists 

 of more or less spherical or oval lumps of con?iderable size piled together, 

 is an obvious factor in fixation ; for it provides the crevice or recess in 

 which a favoured rudiment may begin its development and then, by 

 mutual opposition of its parts, presses against the sides of the solid 

 stipe-base so that the latter becomes firmly wedged in between the dung- 

 balls, between or through which it has to grow. The very base or 

 first-formed part of the stipe-base is attached to the myceHum within 

 a dung-ball and to the mycehal stratum (with its mycelial strands) 



