COPRINUS CURTUS 23 



The Periodicity in Fruit-body Development. — When fresh 

 horse-dung balls are placed in closed crystallising dishes in the 

 laboratory at Winnipeg, a crop of Coprinus curtus fruit-bodies 

 usually appears upon it after about ten days ; and, thereafter, 

 new crops of fruit-bodies come to perfection each day for many 

 days in succession. The expansion of the pileus culminating with 

 the discharge of the spores — a process which occupies about an 

 hour in dwarf fruit-bodies and three or four hours in very large 



m % %J^mmM 



Fig. 17. — Coprinus curtus. Spores whicli fell on to a glass slide and 

 were pliotographed dry. Their oval form and deep black appear- 

 ance are well shown. Magnification, 500. 



fruit-bodies (Figs. 3, 4, and 5, pp. 7, 8, and 10) — always takes 

 place in the morning. In the afternoon an active culture contains : 

 (1) collapsed fruit-bodies which shed their spores in the morning, 

 and (2) rudimentary fruit-bodies at the surface of the dung, a few 

 mm. high, which are destined to elongate their stipes during the 

 night and to shed their spores the next morning. This periodicity 

 in the development of fruit-bodies, as is shown by a series of ex- 

 periments about to be recorded, is regulated by daylight. 



One evening a culture of Coprinus curtus, like that just described, 

 was placed in a dark-room. Next morning, in the dark, a new 

 crop of fruit-bodies expanded and shed their spores in the usual 

 way. This experiment, which was repeated subsequently, proves 



