COPRINUS CURTUS 



17 



spherical shape and becomes irregular, thus reveahng the colloidal 

 substance which they contain (Fig. 12, c-/).^ 



The Caulocystidia.— The caulocystidia resemble the pilocystidia 

 in structure and function. Those at the base of the stipe are formed 

 first and, as the stipe increases in length by intercalary growth just 

 beneath the pileus, new caulocystidia are developed in acropetal 

 succession. Thus the whole stipe becomes finely villose. A young 

 fruit-body with an unexpanded pileus was placed in a compressor 

 cell in air saturated with water-vapour. Immediately drops were 



H 



«l 



f 7>l. 



Fig. 11.— Coprinus curtus. Pileal hairs (pilocystidia): a, a young hair, half-grown, 

 showing protoplasmic contents, as yet not capitate, accompanied by two 

 scale-cells; h, a full-grown hair showing vacuolated contents; c-k, nine hairs 

 showing variations in size and shape ; all are capitate, the bases of some are 

 rounded and of others pointed ; I, the end of an abnormal hair which has lateral 

 instead of a terminal capitulum. Magnification, 293. 



excreted at the ends of the caulocystidia and pilocystidia. Then 



the fruit-body was exposed to dry air for some hours. As it dried, 



the drops slowly shrank and disappeared, leaving a film of mucilage 



behind, and the hairs became twisted. The fruit-body was then 



once more placed in air saturated with water- vapour. In the course 



of about half an hour a number of the caulocystidia recovered, and 



some of the drops grew to their former size. The stipe contained 



no water, and it therefore seems probable that the dried mucilaginous 



matter of the drops absorbed water from the air and then passed 



some of it into the shafts of the hairs. Knoll has supposed that 



the pilocystidia and caulocystidia act as hydathodes and assist 



^ The drops excreted by the sporangiophore of Pilobolus and by the hyphae of 

 the mycelium of Coprinus sterquilinus also dry up with an irregular surface and are 

 therefore also colloidal. 



VOL. IV. c 



