THE DEVELOPMENT OF CORTINARIUS PHOLIDEUS 53 1 
Fig. 15. Left side of preceding figure, more highly magnified. On the outside 
are the large hyphae of the outer blematogen layer, with an outward and upward 
direction. Within is the inner blematogen layer, composed of slender parallel hyphae, 
interlacing with the surface of the pileus above its margin. Below the hymenophore 
is the gill cavity. X 1 15. 
Fig. 16. Right side of median longitudinal section of a fruit-body a little older 
than the preceding one. The palisade zone is differentiated and the gill cavity is 
completed. Extending up over the edge of the pileus margin may be seen hyphae 
of the inner part of the blematogen. X 1 15. 
Fig. 17. The right side of median section, showing the palisade layer and the 
universal veil, with the loose area between the latter and the pileus surface. X25. 
Fig. 18. Median section of fruit-body after the gills are formed. The pileus 
and stem have become very compact through branching and growth of their hyphae. 
The pileus margin is strongly inroUed, as in all the fruit-bodies sectioned at this 
stage. The cells of the blematogen hyphae are collapsed and shrunken and show 
signs of aggregation into the tufts that later become the erect squamules on the sur- 
face of pileus and stem. The narrow area of loose tissue between blematogen and 
pileus surface may be seen here. X 15. 
Fig. 19. A fruit-body a little younger than the preceding, showing well the 
radiating hyphae of the blematogen. X 15. 
Plate XXIX 
Fig. 20. The section represented by this photograph is from a fruit-body at a 
stage after the gills are well formed. The margin of the pileus is strongly incurved 
and the edge is free from the veil. X30. 
Fig. 21. This section shows well the structure of the cortina. It is composed 
of the slender hyphae of the inner part of the blematogen and the marginal veil. On 
the outside are remnants of the outer layer of the blematogen. Since the pileus 
margin is not strongly inrolled in this particular fruit-body, the edge has not become 
free from the veil. X30. 
Fig. 22. A portion of the right side of a section showing the pileus with its 
edge entirely free from the cortina, due to its inrolled character. X30. 
Figs. 23-27. A series of sections showing the origin and development of the 
lamellae. In Fig. 23 a section near the pileus margin is shown. In the center is the 
well developed gill cavity. Above it is the even palisade area of the hymenophore, 
bordered on either side by primordial tissue. Below is loose ground tissue on the 
stem. In Fig. 24 the first gill salients are seen as two slightly downwardly projecting 
broad folds in the palisade. Fig. 25 shows these two salients better developed, 
toward the stem, and at the right a third is appearing. Fig. 26 represents a section 
of the same fruit-body tangent to the stem. On the left is the level palisade and on 
the right development has proceeded further, so that a gill salient has been formed. 
Fig. 27 is of a section nearer to the center of the fruit-body, showing the same features 
as in the preceding section. X112. 
Figs. 28-32. Stages in the origin and development of a dichotomous gill 
through the branching of a gill salient. The section shown in Fig. 28 is near the 
stem, and the following figures are nearer the pileus margin in order. X50. 
