368 Harper.—Sexual Reproduction in Pyronema 
during the process of cutting out the ascospore. Probably 
the nucleus with the beak is a centre for this metabolic 
activity, the kinoplasmic material being distributed from the 
point of the beak as I have endeavoured to show more fully 
elsewhere. The process of growth of the rays and their fusion 
into a membrane continues backward around the nucleus 
until the latter is entirely enclosed in a new bounding mem¬ 
brane, and the spore is thus completely deliminated by the 
process of free cell-formation. Later, a wall is developed 
around the spore, which in Pyronema never becomes especially 
thickened or sculptured. The ripe spores remain uninucleate. 
Their germination I have not studied. 
A section through a mature compound apothecium is shown 
in diagram by Fig. 23. The secondary mycelium shown at 
this stage begins its development as an outgrowth from the 
superficial cells of the hypothecium in stages a little older 
than that shown in Fig. 20. These filaments may arise from 
any one of the hyphal cells which is on the surface. They 
are extremely thick, at least twice the diameter of ordinary 
filaments, and extend downward and outward until they 
reach the substratum, where they mingle with the hyphae 
of the mycelium. Their existence is necessary for the support 
and attachment of the fruit-body, since it would otherwise 
have only the original thickened hyphae of the cluster which 
bore the sexual organs as a connexion with the substratum. 
Whether these appendages also serve to draw up water and 
food from the substratum is uncertain. Their protoplasm is 
vacuolated. They are sparingly septate, and their cells are 
multinucleate. They are plainly similar to the supporting 
hyphae I have already described for Ascobolus ( 16 ), and are 
probably homologous with the more highly differentiated 
appendages of the Mildews. As already noted, the apothecium 
of Pyronema is a compound structure built up of the asco- 
genous hyphae and vegetative tissue developed in connexion 
with several pairs of sexual organs. Fig. 23 represents two 
ascogonia at the base of the fruit-body. In such cases as 
this it is very plain that the main development of the asco- 
