342 RESEARCHES ON FUNGI 



toward the stipe, in cross section they are far from having the regular 

 and pronounced wedge shape so characteristic of the Aequi-hymenii- 

 ferae (c/. Fig. 152 with Figs. 85 and 139 in Vol. II, pp. 249 and 390). 



The cystidia, which can be seen with the naked eye as glistening 

 particles, are practically confined to the halves of the gills which 

 are nearest to the stipe, and they are especially numerous at the 

 free margins of the shorter gills (Fig. 152). In the young and 

 unexpanded pileus some of them appear to stretch right across the 

 interlamellar spaces, but others do not (Fig. 152). They certainly 

 make it impossible for the opposing faces of adjacent gills to come 

 into contact. After cutting and examinmg a number of sections like 

 that shown in Fig. 152 as carefully as possible, I came to the con- 

 clusion that the distance-piece function of many of the cystidia is 

 never called into play and, therefore, that many of the cystidia act 

 merely as guards. The mechanical employment of any cystidium 

 appears to depend on circumstances. During the development of 

 the pileus, should two adjacent gills approach too near one another, 

 the cystidia in the interlamellar space act as mechanical obstacles 

 and prevent contact of the hymenial surfaces being made ; but, 

 should two adjacent gills not approach within a certain distance of 

 one another, the cystidia project freely into the interlamellar space 

 in a peg-like manner and have no mechanical work to do. This 

 is a very different arrangement from that which has been already 

 described for Cop-inus atramentarius, where every cystidium with- 

 out exception acts as a distance-piece until its destruction by 

 autodigestion (c/. Fig. 122, p. 287). 



On examining the hymenium of Coprinus micaceus in face view 

 with the high power of the microscope, one can readily perceive the 

 dark spores standing out upon a lighter background. An exact 

 plan of the position of the spores over a, two-hundredth part of a 

 square mm. is shown at A in Fig. 153. At first glance, the spores 

 on such an area may appear to be very irregularly arranged ; but, 

 if one focusses up and down with the aid of the fine adjustment, 

 one quickly discovers that some of the spores stand in part verti- 

 cally above others ; so that, after all, there is no jostling of one 

 spore by another. With a little care, one can resolve the spores 

 into four sets according to the height at which they stand above 



