190 RESEARCHES ON FUNGI 



spaces must be developed in some other manner. This is done in 

 Coprinus sterquilinus : firstly, by the slight expansion of the pileus 

 so that the gills are suitably spaced where they adjoin the pileus- 

 flesh and, secondly, by the production of flanges where the gills 

 come together in the neighbourhood of the stipe (c/. Figs. 78 and 

 79). Further, the gills are somewhat thicker and correspondingly 

 stiffer than they are in Coprinus atramentarius and other species 

 where the cystidia act as space-making organs. Thus, owing to 

 the fact that adjacent gills are separated from one another both 

 near the pileus-flesh and near the stipe, and to the fact that the 

 gills are sufficiently rigid so that sagging does not occur in their 

 central parts, the interlamellar spaces necessary for the free, develop- 

 ment of the basidia are maintained in existence. 



The gills are not all of one length but, just as in Psalliota cam- 



pestris and other Agaricineae with large fruit-bodies, are of various 



lengths (Fig. 80, B). The longest gills, which in one fruit-body 



were found to be forty in number, stretch from the periphery of 



the pileus to near the stipe where they unite and form a collar 



(Fig. 80, c). This collar resembles that of Coprinus plicatilis and 



is attached to the flesh of the disc at a radial distance from the 



stipe of 1-2 mm. The gills of Coprinus sterquilinus, therefore, in 



the language of the field mycologist, are free from the stipe. The 



gill-system is irregular, and it is impossible to separate the gills 



into natural classes with special limits of length for each class. As 



two adjacent long gills pass from the collar to the pileus-periphery, 



they diverge, and, when the divergence has attained a certain 



degree, a new and shorter gill arises in the interlamellar space 



between them and proceeds to the pileus-periphery. Other still 



shorter gills may arise nearer the periphery of the pileus in a similar 



manner. The number, length, and arrangement of the gills in 



the gill-system is such that the pileus in the barrel-shaped condition 



contains just as many gills packed side by side as there is room for, 



due provision being made for the interlamellar spaces required 



for the development of the projecting basidia. The development 



of the gill-system is beautifully regulated, so that the gills are never 



overcrowded and never too few to occupy fully the space at their 



disposal. 



