COPRINUS STERQUILINUS 163 



arises ; for, owing to the presence of the numerous hyjjhal bridges, 

 there will always be plenty of channels leading to it. 



The fruit-body shown in Fig. 90, D, finally elongates its stipe, 

 expands its pileus, and discharges its spores. Then the whole 

 of the mycehum is exhausted and no more fruit-bodies can be 

 produced. 



(2) Now let us suppose that, in a dung-ball of the same size as 

 before, not one spore but one hundred spores are present. Let the 

 spores be scattered uniformly in the dung-ball, as shown in Fig. 91, 

 A. At B the spores have germinated and each spore has produced 

 a young mycelium. At this stage of development the mycelia are 

 competing with one another, for each mycelium is using up the food 

 materials in its vicinity and, by radial growth, is invading fresh 

 territory. Soon, however, as shown at C, the myceha come near 

 to one another peripherally. What happens next ? After the 

 individual mycelia have become diploid, or possibly before, hyphal 

 fusions take place in each mycelium and between adjacent mycelia, 

 so that the one hundred mycelia soon become converted into one 

 single diploid closely- woven three-dimensional network. This 

 compound mycelium in proceeding to reproduction, as shown at D, 

 behaves just like the single monosporous mycelium already considered 

 (c/. Fig. 91, D and Fig. 90, D) : it gives rise to a si7igle large fruit- 

 body. Again the hyphal bridges come into play, and the hquid 

 contents of the mycelial hyphae flow from all directions tow^ard 

 the fruit-body, thus enabling it to complete its development ; and 

 soon the fruit-body lengthens its stipe, expands its pileus, and 

 liberates its spores. 



The production of a single fruit-body of Coprinus sterquilinus 

 from (1) a mycelium of monosporous origin and from (2) a myceUum 

 of polyporous origin in two actual cultures, which were started on 

 the same day, is shown in the photograph reproduced in Fig. 92. 



Fig. 91 — cont. 



but, owing to the fact that all the mycelia have united and have acted together, 

 it has been pos.sible for a fruit-body to be produced on one of the rnycelia, so 

 that complete sterility of the whole group of mycelia has been avoided, with 

 consequent benefit to the species as a whole. The numerous hyphal fusions, 

 which here can have no possible sexual significance, are important in that they 

 permit the various monosporous mycelia to act together socially in tlie pro- 

 duction of a fruit-body and also in that they make possible the conveyance of 

 food-materials to the fruit-body tlu-ough niunerous channels. 



