﻿igi6] ■ ATKINSON— COPRINUS gg 



with their axes (through or between them) in the median plane. 

 Also, as the sections pass out of the stem, on the far side, the 

 middle area is devoid of the salients, as on the near side, until 

 the sterile area between the stem and young hymenophore has 

 been passed. 



In the tangential sections, therefore, far enough away from the 

 stem to clear this sterile area, the salients over the middle portion 

 are cut squarely in a transverse direction, while those on either side 

 are slightly oblique, those at the extreme ends (sides) being slightly 

 more so than those nearer the middle. But the salients are so 

 small and narrow, and at this time extend radially to such a short 

 distance, that it is very difficult, if not impossible, to appreciate 

 the differences in the direction of the cut. At this earliest stage 

 in the origin of the lamellae, the salients do not extend to the 

 extreme margin of the cavity. From the area of salients there is a 

 gradual transition in a centrifugal direction to the plain palisade 

 area, and from this to the frazzled area at the extreme margin. 

 For this reason the tangential sections through the area of the 

 salients at this time show that the salients are confined to the middle 

 portion, and the transition outward toward the margin on both 

 sides passes into the palisade area and then into the frazzled area 

 at the extreme margin (figs. 13, 15). 



The first salients, or ridges, which appear in the young h}-meno- 

 phore are short, radial, downward projecting folds of the palisade 

 layer. They are the fundaments of the primary lamellae them- 

 selves. They are formed by the increase and enlargement of the 

 elements of the palisade layer along radiating lines. The increased 

 pressure thus brought about in the palisade area causes a downward 

 arching of these radial areas of the palisade, accompanied by the 

 downward growth of the trama hyphae of the pileus along these 

 radial areas, thus forming the trama of the young lamellae. The 

 trama hyphae of the young lamellae are rather weakly developed, 

 in contrast with the strong development of the hyphae of the pali- 

 sade layer, being more slender, of less protoplasmic content, and 

 forming a rather loose mesh. 



The origin of the lamellae is very clearly shown in figs. 13-16. 

 Fig. 14 is from a section just passing out of the sterile area on the 



