126 RESEARCHES ON FUNGI 



of Coprinus sterquilinus were to make the same bold curvatures in 

 response to light as those made by the tiny fruit-bodies of C. niveus 

 and C. curtus, there is no doubt that disaster would result : the 

 stipes would either topple down or break. We may conclude, 

 therefore, that smaller Agarics and larger ones have different modes 

 of reacting to the tropic stimuU of Ught and gravity, each mode 

 being beautifully suited to the mechanical qualities (size and weight) 

 of the two classes of fruit-bodies. 



The Mechanical Fixation of the Fruit-body. — In order that the 

 millions of spores which are developed on the under side of the 

 pileus shall be freely liberated into the air and thus be carried off 

 by the wind, it is necessary that the fruit-body as a whole shall be 

 firmly fixed in its substratum. Mechanical fixation is as important 

 for a fruit-body as it is for a tree. In a Phanerogam the fixed 

 position of a stem is fraught with various advantages : it enables 

 the leaves to take up an optimum position in respect to the light 

 and so aids the process of photosynthesis, it allows of the flowers 

 being oriented so that pollination may be properly effected, and it 

 often permits of the seeds or fruits being liberated in such a manner 

 that they may be readily disseminated by the wind or by animals. 

 In such a fungus as Coprinus sterquilinus, however, the fixed position 

 of the fruit-body is related to one function only, the production and 

 hberation of the spores ; but upon the successful carrying out of 

 this the whole fife of the species — its persistence from one generation 

 to the next — absolutely depends. 



The fruit-bodies of Coprinus sterquilinus, which require to be 

 firmly fixed, are, as we have seen, of considerable size and weight. 

 In a normal, well-grown fruit-body, the height is 6-10 inches and 

 the width of the fully-expanded pileus 2-4 inches ; but, in very 

 large fruit-bodies which appear from time to time in artificial 

 horse-dung cultures, the height may be as great as 11-12 inches 

 and the width of the pileus 5-6 inches. One large fruit-body, as 

 already recorded on a previous page, was found to have a weight of 

 27 grams, or nearly 1 oz., and to have its centre of gravity situated 

 at a distance of 5-5 inches from the base of the stipe. Coprinus 

 sterquilinus is strictly coprophilous and always grows on horse 

 dung. Therefore, the substratum to be considered in connection 



