1g9t0) MCCUBBIN—DEVELOPMENT OF THE HELVELLINEAE 199 
early stages, and persisting throughout life on all but the hymenial 
surface, is a “palisade layer.” This layer is formed from club- 
Shaped ends of the hyphae, which arrange themselves closely and 
evenly at right angles to the surface. In early stages this layer is 
not well differentiated. Later on it becomes more regular, its threads 
take on a more pronounced club shape, and the cells become filled 
with deeply staining contents. 
THE MEMBRANE.—The envelope which covers the fruiting body 
in its early stages arises from the palisade layer. Many of the club- 
shaped hyphae of the latter continue to grow out beyond the general 
surface, then turn at right angles, and interlacing in every direction 
along the surface form a matted web 2-8 threads in thickness. This 
membrane is very transitory, however, and undergoes degeneration 
at an early period. Its protoplasm takes on a granular appearance, 
the cell outlines become indistinct, and finally the whole disintegrates 
into a deeply staining mass in which the nuclei are the most prominent 
feature. Long before this process is complete, however, the rapid 
growth of the underlying tissue bursts the emvelope so that it adheres 
in flakes ( jigs. 57, 58). Then the paraphyses and intercalary palisade 
hyphae pushing out to the surface complete the separation and all 
traces of it are cast off. 
DuRanD, in speaking of this veil in Microglossum viride, states 
that “when the veil seems to break up into fragments, there are indica- 
tions that the hymenium first appears through a pore at the apex.” 
This phenomenon has been homologized with the opening of the 
apothecium in Ascobolus. But the coverings of Spathularia, Leotia, 
and Mitrula break up irregularly without any indication of an 
apical pore, and in Helvella elastica also it breaks irregularly. More- 
Over, in some forms a veil may be altogether lacking. Indeed I am 
able to state definitely, from observations on a very complete series 
of stages, that Geoglossum hirsutum shows no trace whatever of such 
a structure. 
THE PARAPHYSES.—In sections of young ascomata of Helvella 
élastica the hymenial surface is not yet differentiated, being quite 
Similar to that in other parts of the fruiting body, and covered by the 
common palisade layer and external veil. Very early, however, the 
Paraphyses begin to appear, and as these force their way upward 
