214 BOTANICAL GAZETTE [SEPTEMBER 
is completely free. That this ground tissue has nothing to do with 
the formation of the palisade is shown by the fact that, as already 
stated, it is attached indifferently to the hymenophore primordium, 
and in many cases is largely broken away from the tufts and between 
them before the palisade layer is formed. Furthermore, these tufts 
of the hymenophore primordium are not the primordia of the 
lamellae, since before the origin of the latter they become lost in the 
even palisade (figs. 17, 18). In those instances where the ground 
tissue remains adherent to the edges of the lamellae for some time, 
and not to the palisade between them, it is due to the fact that 
through the downward growth of the gills the strands of hyphae 
attached to their edges are subject to less strain than the hyphae 
attached between them, and so keep their attachment longer. 
The downward growth of the lamellae may be partly initiated 
by the pressure in the palisade layer due to the rapid growth and 
enlargement of its hyphae, which would produce a tendency to 
throw the palisade into folds.. The chief agency in their formation, 
however, seems to be the downward growth of radially arranged 
groups of hyphae in the hymenophore, which are very active in 
growth at this time, as indicated by their deep stain. These radial 
lines of deeply staining hyphae push down into the folds of the © 
_ palisade and form the trama of the gills (figs. rg-21). The further 
_ growth of the lamellae in depth takes place by apical and interstitial 
growth in the trama. Later stages in development (fig. 23) show 
the hyphae from the trama turning outward on all sides to add to 
ee et Oe lates ret ea 
| : Pholiota flammans . 
— OF BASIDIOCARP.—The very young ionlt: bois, = 
efore any internal differentiation has taken place, is a compact 
_ structure, composed of slender, intricately interwoven hyphae, 
ae . ed H in diameter, and rich in protoplasm. The hyphae havea 
__ general direction of growth away from the substratum n, and many 
