1918] FITZPATRICK—RHIZINA 213 
cells of the ascogenous hyphae become vacuolated, stain lightly, 
and apparently take no direct part in the formation of the 
hymenium. 
The layer of paraphyses is developed early in the history of the 
fruit-body and constitutes a well defined zone long before the 
young asci are developed. This zone is in reality merely a differ- 
entiation of the palisade layer of peripheral vegetative hyphae, and 
its elements have no direct organic connection with the archicarp or 
ascogenous hyphae. 
Early in the history of the archicarp there are developed also 
paraphysis-like structures, termed setae, which originate far below 
the hymenium from vegetative hyphae, traverse the hymenium, 
and protrude beyond it as thick-walled, dark-colored spines. These 
spines are non-septate tubes which discharge at their tips a brown, 
glutinous secretion over the surface of the hymenium. 
The terminal branches of the ascogenous hyphae push up to 
the base of the paraphysis layer, and there undergo typical crozier 
formation. The terminal portions of the hyphae are of smaller 
diameter than the cells nearer the archicarp. The tip of each 
branch contains two nuclei, and in some cases these are cut off 
from the remainder of the thread by a septum. The nuclear mem- 
brane is sharply defined and the nucleolus stains deeply. The 
two nuclei are in some cases closely approximated or actually in 
contact, while in others they lie relatively remote from each other. 
The tip of each branch of the ascogenous hyphae forms a single 
definite hook (figs. 14-21). Although irregular hooks (figs. 17, 18) 
are not infrequent, complex systems of hooks such as those described 
by CraussEn (17) in Pyronema confluens, by BROWN (11, 12) in 
Leotia, Lachnea, and Geoglossum, and by McCussin (53) in Helvella 
elastica have not been found. 
The two nuclei in the tip of the hypha at the time of crozier 
formation probably undergo conjugate division in the usual manner. 
Four nuclei (figs. 19-21) thus result. These drift apart, the 
uppermost pair passing into the bend of the hook, which then under- 
goes renewed growth and develops a prominent “dome cell” 
(fig. 21). The other pair of nuclei come to lie in such a position 
that one occupies the recurved tip of the hypha and the other the 
main body of the thread. The two septa frequently figured in 
