154 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Cultivation of Michenera spores. — Germination of the thick-walled 
mature spores was obtained in but few instances; very strongly con¬ 
centrated potato-agar gave the best results. Younger spores ger¬ 
minate much more readily; in fact, if the spore is not fully mature and 
some protoplasm still remains in the shaft or appendage, this fre¬ 
quently puts forth a hypha, while the spore proper remains unchanged 
(pi. 18, fig. 14). This should not be regarded as germination of the 
spore, but merely as a continuation of the vegetative growth. From 
three to four days are normally required for the germination of mature 
spores. The number of germ tubes is frequently as high as three or 
four from a single spore, one commonly making its appearance 
through the empty shaft (pi. 18, fig. 15). The mycelium produced 
is indistinguishable from that arising from a basidiospore, and, like 
it, soon forms Michenera fructifications, but has not thus far pro¬ 
duced basidiosporic hymenia. Although the chain of evidence is 
incomplete through the absence of this last link, yet the identity of 
Corticium subgiganteum and Michenera artocreas as stages in the 
development of one fungus seems sufficiently demonstrated by the 
absolute similarity of the mycelia, and especially by the constant 
and regular'production of Michenera fructifications in cultures of the 
basidiospores. 
Development of fructification and spores of Michenera artocreas .—- 
The spores grown in agar tubes agree perfectly with those produced 
under natural conditions in the field, but are heaped up in a pustule 
without the formation of a cup. In wood cultures, too, the sides of the 
cup are much lower than in Nature and frequently appear only when 
the fructification is sectioned, being completely submerged by the 
copious production of spores. In such cases the general appearance 
of the fructification strongly resembles that of Hypoxylon. Culture 
conditions appear to disturb the normal process of development, and 
to produce a stimulation of spore formation at the expense of the sterile 
parts of the cup. Hence the following account of the development of 
the fructification is taken from specimens collected in the field. 
The first appearance of the cup is a small pyramidal growth of 
hyphae, faintly brownish tinted on the exterior. A longitudinal sec¬ 
tion frequently reveals concentric brownish layers which mark the 
successive periods of growth in the intermittent development of the 
pyramid. The hymenium originates at the apex of the pyramid 
where the hyphae begin to form spores and a brown spot appears- 
