420 DR. D. D. CUNNINGHAM ON THE CONIDIAL 
that the forms of asexual fructification observed by them were either sporangial or 
chlamydosporic, at once conclude that conidial forms never can occur. 
In reference to Brefeld’s observations, it is of importance to note that he knew 
Chetocladium and Piptocephalis, his conidial genera, only as parasitic organisms, that — 
is, only under conditions in which their nutrition was at its highest,—conditions which ` 
the phenomena of Choanephora justify us in regarding as those securing the production ` 
of a luxuriant mycelium, occasionally of the sexual fructification, and constantly of the 
conidial form of asexual fructification. 
MM. Van Tieghem and Le Monnier, however, studied one of these genera, Cheto- — 
cladium, under different circumstances. They observed it not only as a parasite on 
other Mucorini, but as growing independently and deriving its nourishment directly — 
from the surrounding media. In reference to the conclusions of these observers 
regarding the nature of the fructification in this genus and in Piptocephalis, three possi- — 
bilities suggest themselves in endeavouring to reconcile their statements with those of — 
Brefeld. It may be (1) that in both genera they only met with true sporangial fructi- 
fication; or that (2) they encountered both sporangial and conidial forms; or possibly 
even (3) that in certain cases they met with conidial forms alone. It may appear to be 
presumptuous to suggest the latter two possibilities; but when carefully studied in 
connexion with the present series of observations, their interpretations of many of the 
phenomena actually observed appear to have been in some degree influenced by a fore- 
gone conclusion of the impossibility of the occurrence of conidia. In reference to the 
possibility of the form of fructification observed by MM. Van Tieghem and Le Monnier | 
having been of a different nature from that obtained by Brefeld in his cultivations, it 
may be noted that the former authors give an account of the phenomena attending 
germination in Chetocladium differing materially from that furnished by Brefeld. 
They affirm that germination occurs with hardly any antecedent enlargement of the 
spores ; Brefeld describes the conidia as enlarging considerably prior to germinating. 
The grounds on which there is reason to suspect that the interpretation of phenomena 
given by MM. Van Tieghem and Le Monnier has occasionally been somewhat influ- 
enced by a foregone conclusion, and by a desire to avoid the complication incident on the 
recognition of two subfamilies of Mucorini, as proposed by Brefeld, must be considered 
somewhat in detail in order to be appreciated. 
In reference to Chetocladium, these writers allow that the bodies which they regard 
as sporangia invariably contain only a single spore. Here the question at once arises, 
How are monosporous sporangia to be distinguished from conidia? MM. Van Tieghem 
and Le Monnier apparently distinguish them by the fact that in germinating, or when 
exposed to pressure, the contents of the cell, if of a sporangic nature, escape, partially or 
completely, as a homogeneous spore-like body. But such a phenomenon may surely 
occur in conidia‘ or spores in which there has been a distinct formation of a firm exospore 
including an endosporic sac. If one look for examples of such an occurrence among 
kibori; although cases of complete escape of the endospore are perhaps unknown, 
there is no great difficulty in obtaining examples of partial escape. Tuniak to MM. Yon 
Tieghem and vs Monnier’ s own account of the germination of the spora | es of 
