ADJUSTMENTS OF FRUIT-BODIES 75 



A diurnal rhythm in the development of the fruit-bodies of 

 small and ephemeral Coprini occurs not merely in the laboratory 

 but also in nature. I have noticed it more particularly in the case 

 of Coprinus iDlicatilis growing on a lawn. A few fruit-bodies came 

 to maturity toward each noon for a succession of 20-30 days. 

 Worthington Smith ^ noticed the same phenomenon for Coprinus 

 radiatus growing on a manure heap. He states that " at seven 

 or eight in the evening nothing but immature plants can be seen ; 

 about eleven or twelve a rapid growth commences, and by two 

 or three o'clock in the morning perfect maturity is reached. If 

 the morning is moist the plants will remain in perfection till nine 

 or ten o'clock, but if it is dry they will not last after five or six." 

 According to these observations, in nature the fruit-bodies of 

 Coprinus radiatus may shed their spores before daylight appears. 

 If this is so, strong support is given to my view that the importance 

 of the periodic development lies, not in spore-liberation occurring 

 at any particular time, but in the fact that the beginning of the 

 stretching of the stipe is arranged to take place whilst light can 

 be used as a directive stimulus. 



The adjustments of the fruit-bodies of Coprinus pUcatiloides 

 in the interests of spore-liberation may be summed up as follows : 



(1) Heliotropic curvature of the stipe, w^iich causes the pilei to 

 be brought out of crevices in the substratum into the open ; 



(2) erection of the pileus by a negatively geotropic curvature of 

 the stipe ; (3) raising of the pileus by the elongation of the stipe ; 

 and (4) adjustment of the gills by the expansion of the pileus. 

 There is no deliquescence of the gills, and on this account the 

 fruit-bodies of Coprinus pUcatiloides have one adjustment less 

 than those of Coprinus niveus. 



General Remarks. — A number of otherwise very different copro- 

 philous fungi resemble one another in reacting to light. Thus we 

 find that positive heliotropic curvatures are made, not only by the 

 stipes of the Coprini, but also by the sporangiophores of Mucor, 

 Phycomyces, and Pilobolus, by the asci of Ascoboli, and by the 

 perithecial necks of Sordariie. These responses to light are admir- 



^ W. Smith, " Keproduction in Coprinus radiatus" Grevillea, vol. iv., 1875-76, 

 p. 54. 



