LYMAN: STUDIES OF HYMENOMYCETES. 
163 
it differs from the latter; first, in its greater duration, the secondary 
or clamped mycelium not appearing for from ten to twelve days; and, 
second, in the increased production of conidia, which are frequently 
formed sparingly in cultures from basidiospores, but always in abun¬ 
dance when the culture originates from a conidium. In succeeding 
generations of cultures from conidia the formation of these spores 
becomes more and more copious, and the appearance of the secondary 
mycelium is longer and longer delayed, until in some cases the clamped 
hyphae fail to appear at all during the entire life of the drop culture. 
If transferred to an agar tube, however, the secondary mycelium finally 
develops, and is followed by the production of bulbils as in the case of 
cultures from basidiospores. Thus it appears that the conidia belong 
essentially to the primary mycelium, because they are produced by 
primary hyphae, or by branches from the early growth of the sec¬ 
ondary mycelium which resemble primary hyphae, because they in¬ 
variably give rise to primary mycelia on germination, and because 
continued cultivation of conidia causes the characteristics of the 
primary mycelium to become intensified, and separates the latter more 
sharply from the secondary mycelium. The significance, if there is 
any, of this separation into primary and secondary mycelia has not 
been determined. 
The nature of the conidia .— It is evident that in certain respects 
these bodies, which we have called conidia, closely resemble oidia. 
The occasional breaking up of the whole hypha into a chain of spores 
is exactly comparable to the formation of oidia; but such a case is 
the exception, not the rule. Moreover, the cutting off by a mere sep¬ 
tum, without the formation of a constriction or sterigma, of a cell 
having the same diameter and appearance as the parent hypha, is a 
type of spore formation which is decidedly inferior to that ordinarily 
pertaining to conidia, and closely resembles the production of oidia, 
which are merely segments of the parent hypha. On the other hand, 
the character of true conidia is shown (1) by the differentiation of a 
rather definite sporophore which may be quite easily distinguished 
from the vegetative hyphae; (2) by the early disappearance of the 
sporophore after the separation of the spores, while the latter retain 
their vitality for a slightly longer period, thus indicating that we have 
here not merely vegetative cells, but a definite reproductive mechanism 
showing some differentiation; (3) by greater uniformity in shape, size, 
and general appearance of the spores than is usually seen in oidium 
