14 BOTANICAL GAZETTE [july 



these may be seen in figs. 76 and 92. Here some are shown that 

 are still in the young salient condition, and two others that have 

 started near the point at the upper portion of the pileus at which the 

 section was cut off and developed outward. These 2 gills are dis- 

 tinguishable by their narrow attachment to the upper portion of 

 the pileus. The location of the secondary gills is clearly shown in 

 a horizontal section through the pileus (fig. 77). 



The primary gills very commonly branch as they develop. 

 The branching is frequently dichotomous, but may be of various 

 types, as is illustrated in fig. 77. These branches seemingly arise 

 in much the same manner as described by Sawyer (18) for Cor- 

 tinarius pholideus. 



During the expansion of the gills the hyphae making up| the 

 trama become much enlarged and separate from each other, so that 

 a very loose open trama results. Fig. 90 shows the structure of a 

 gill at maturity, and a comparison with fig. 89 shows the changes 

 taking place during the expansion of the fruit body. 



CHANGES TAKING PLACE IN BLEMATOGEN DURING DEVELOPMENT 



As the blematogen is first differentiated it consists of loosely 

 interwoven filaments, which take the stain quite deeply (figs. 51-55). 

 The cells composing it soon lose their protoplasmic content, how- 

 ever, the individual cells becoming inflated to 4-6 /i in diameter 

 and the blematogen showing as a very thin layer of loosely arranged, 

 weakly staining filaments covering pileus and stem (figs. 56-73). 

 It becomes so delicate that it is easily destroyed even with careful 

 handling. The boundary line between the blematogen and the 

 surface of the pileus is never clearly defined, but at all times the 

 one merges into the other, as described by Atkinson (4, 7) for 

 Agaricus rodmani, A. arvensis, and A. comtulus, and by Allen (i) 

 for Hypholoma. The shedding of the blematogen is somewhat like 

 that in Coprinus micaceus (8) in the manner in which the cells 

 become constricted at the cross- walls and break off, but at no time 

 do they arrange themselves in a definite compact paUsade layer as 

 in C. micaceus. 



During the final expansion the blematogen becomes so thin and 

 delicate that it breaks up into scurfy particles (fig. 74), which, 



