PLUTEUS CERVINUS 105 



wedge-shaped and to have a small flange at their free edge directed 

 toward the stipe. The interlamellar spaces have become slightly 

 widened and are now crossed by numerous fully-developed barbed 

 cystidia which everywhere beset the hymenium (Fig. 48). The 

 microscopic appearance of a gill at this stage of development is 

 shown in face view and in cross-section in Fig. 49 at C and D re- 

 spectively. A study of these two drawings shows that of the three 

 classes of elements which make up the hymenium, namely, cystidia, 

 basidia, and paraphyses, the first-named are the first to attain 

 maturity : the cystidia have already grown to their full length 

 and have developed their hooks before any rudiments of spores 

 or even of sterigmata have begun to appear on the basidia. 



As a pileus expands, the gills are raised into more or less hori- 

 zontal positions (C and T> in Fig. 47) and, at the same time, they 

 separate from one another, so that the interlamellar spaces increase 

 greatly in width. A vertical section through parts of two gills and 

 an intervening interlamellar space is shown in Fig. 49 at E. At this 

 stage of development the cystidia no longer cross the interlamellar 

 spaces but merely project from the hymenium like so many pegs, 

 and the basidia are freely discharging their spores. 



The spore-picture presented by a surface view of the hymenium 

 when shedding spores (Fig. 50, A and B) is similar to that already 

 several times described for the Armillaria Sub-type. The only novel 

 point is the presence of the barbed cystidia. As in Armillaria 

 mellea, Marasmius oreades, etc., on any very small area of the 

 hymenium one sees spores in all stages of development, and one can 

 observe that basidia bearing spores of about equal age in develop- 

 ment are usually w^ell separated from one another. 



A transverse section through a gill (Fig. 51) shows the hymenium, 

 subhymenium, and trama. The hymenium is made up of C3'stidia, 

 basidia, and paraphyses. The cystidia (« and b) often have a deep- 

 seated origin, for they can be observed arising from the outer cells 

 of the trama just below the subliymenium. Each cystidium has a 

 fusiform shaft and a free end which expands into a series of hooks. 

 The hooks on a single cystidium are usually three or four in number, 

 but may be two onl}^ or as many as five (Figs. 49, C, and 50, A). 

 Their shape is also variable. It often happens that a hook is bifid. 



