ipis-] DEVELOPMENT OF AGARICUS RODMAN! 331 



and pileus. This situation is ilhistrated in Figs. 24-31, from selected 

 serial sections of the same basidiocarp. The sections were parallel 

 with the long axis of the stem. Diagrams 5 and 6 illustrate the 

 situation in this basidiocarp and show exactly how the sections were 

 made. 



Fig. 24 is from a nearly median longitudinal section, made in 

 the region indicated by line i of diagrams 5 and 6, which presents a 

 situation practically the same as a median section. The outline of 

 the narrow young gill salient is well shown in- Fig. 24, with the 

 distinct annular cavity. The gill salients are strongly curved and in 

 the form of crescents, the lower limb of the crescent extending far 

 down on the outwardly sloping stem surface ; the upper limb reach- 

 ing out on the under surface of the pileus, where it grades into the 

 level palisade zone, and the latter into the primordial zone. The 

 relation of parts is clearly represented by diagram 5. It is quite easy 

 to form a mental picture of the series of little stalls, or pigeon holes, 

 around the upper part of the stem between these crescentic salients. 



Fig. 25 is from a section in the region indicated by line 2 of 

 diagrams 5 and 6. The line 2 in diagram 6 shows how the section 

 passes through the side of the stem and obliquely across a few of the 

 young gills, then on either side passing through the level palisade 

 and primordial zones. These features are clearly seen in Fig. 25. 

 Fig. 26 is from the region indicated by line 3 : Fig. 27 that of line 4 ; 

 Fig. 28 that of line 5; Fig. 29 that of line 6; and Fig. 30 that of 

 line 7, of diagrams 5 and 6 (figures of sections in the region indi- 

 cated by lines 8 and 9 are not shown from this basidiocarp, but there 

 is nothing essentially different in them from figures 22 and 23 from 

 another plant). Fig. 31 is a more highly magnified view of the 

 middle portion of Fig. 27. 



Figs. 26-29 and 31 present a very interesting situation. They 

 show transections of the stalls, or pigeon holes, mentioned above. 

 Unless caution is observed this situation would be very misleading. 

 The gill salients are attached above to the under side of the pileus 

 and below to the surface of the stem, and this attachment above and 

 below existed from the time of the origin of the salients. However, 

 the attachment below is not that of the margin of the gills, but of 

 their origin from the stem, since the salients grew outward from the 



