I9I5.] DEVELOPMENT OF AGARICUS RODMAN! 333 



Agaricus rodmani (and other species) which may lead to serious 

 misinterpretation unless great caution is observed. This is the rela- 

 tion of the gills to the involute margin of the pileus and to the 

 marginal veil, shown in a series of longitudinal, "tangential" sec- 

 tions of basidiocarps at an age when the gill salients, by centrifugal 

 progression, have nearly or quite reached the margin of the pileus. 

 The various features of this situation are presented in Figs. 32-42. 

 The figures are photographs of selected serial sections from a single 

 basidiocarp. Diagrams 7 and 8 illustrate the situation in this basi- 

 diocarp and the lines show the regions in which the sections were 

 made. 



In Fig. 32, from a nearly median longitudinal section (in the 

 region of line i), the involute margin of the pileus is shown. An in- 

 definite portion of the outer, lighter stained area is the blematogen. 

 The margin of the pileus is so strongly involute that the edge is 

 curved upward toward the gills and has crowded the mass of the 

 ground tissue constituting the inner portion of the veil up against 

 the middle zone of the lamellse. The attachment of this ground 

 tissue to the margin of the gills is not very firm, though there is some 

 adherence of the hyphge. The attachment has occurred after the 

 ground tissue was crowded against the margins of the gills by the 

 strongly upturned, involute pileus margin. The strongly involute 

 margin of the pileus is well shown also in several of the figures in 

 Plate VII. The position of the upturned edge of the involute pileus 

 margin is such that the loose ground tissue of the inner portion of 

 the veil is lifted up against the middle area of the lamellse, while 

 the edges of the gills near the stem and also near the margin of the 

 pileus are free. This is very clearly shown in Fig. 33, from a 

 section in the region of line 2 in diagrams 7 and 8. 



Figs. 34 and 35 are from sections in the region of lines 3 and 4 

 just passing through the surface of the stem in the angle at the junc- 

 tion of the pileus and stem. The hymenophore extends a short dis- 

 tance down on the upper surface of the stem, but the gills are only 

 " adnexed," not extending so far down on the stem fundament as 

 in the basidiocarp represented on Plate XII. and in diagrams 5 and 6. 

 In the middle area of Fig. 35, the nearly solid block of tissue in the 

 same level with the gills on either side, is hymenophore tissue from 



