FRUCTIFICATION OF CHOANEPHORA. - 413 
growth and development have been taking place in the membranes, another series of 
changes has been advancing in the contents. The contents are at first evenly granular, 
but, as maturation proceeds, a separation of oily globules takes place. These globules 
increase in number and size, and, gradually running together, are represented in the 
ripe zygospore by a single large drop of oil. The mature zygospores measure from 0:07 
to 0:05 millim. in diameter. They are covered externally by a thin membrane belong- 
ing to the parent conjugating cells (fig. 16). Their intrinsic membranes consist of a 
thick dark-brown exospore and a delicate colourless endospore (fig. 16). None of those 
tubercles or irregular thickenings of the spore-membranes are present which are so 
conspicuous in the zygospores of other Mucorini; and the ripe structures resemble those 
of some of the Peronosporev rather than those of the nearest allies of the plant. 
According to these observations, the process by which the zygospore of Choanephora 
is formed is intermediate in characters between those occurring in Phycomyces and 
Piptocephalis. The process in common with those of both these genera is carried out by 
the conjugation of two curved cells. It differs from that in Piptocephalis and agrees 
with that in Phycomyces in the simple nature of the union of the conjugating cells. 
On the other hand, it differs from that in Phycomyces and agrees with that in Piptoce- 
phalis in the nature of the phenomena occurring after conjugation, in the unequal 
growth of the combined mass, and the consequent development of a zygospore, which is 
not situated between two lateral suspensors, as in Phycomyces, but is attached by its 
basal aspect to the summit of these structures. 
I have hitherto failed in successfully cultivating the zygospores. The difficulties in 
preserving such bodies in a tropical climate in conditions favourable to germination and, 
at the same time, secure from the attacks of fungi and of animal enemies of various 
kinds, are very great, and frequently almost insuperable. 
The results of the study of the plant under its normal conditions are, then, to show 
that it possesses a mycelium and sexual reproductive apparatus of the recognized Muco- 
rine type, but that the asexual fructification, in place of being sporangial, is of a truly 
conidial nature. | 
After having studied the features presented by the plant in its natural condition, I 
proceeded to undertake a prolonged series of artificial eultivations, with a view of, as far 
as possible, obtaining a complete knowledge of its life-history. Some of these cultiva- 
tions were conducted on a large scale; but the results of these were corrected and 
checked by those of a much more extended series, in which the spores were isolated in 
such small numbers as to allow of ready individual identifications. Some of the latter 
eultivations were conducted on the cellular system, as recommended by MM. Van Tieg- 
hem and Le Monnier *; but the greater number were carried out on the plan originally 
introduced by M. de Bary, and so successfully practised by Brefeld f. There can be 
no question of the theoretical superiority of the cellular cultivations; and the procedure 
* “Recherches sur les Mucorinées.” Par MM. Ph. Van Tieghem et G. Le Monnier. Ann. des Sc. Nat. 5° 
Série, t. xvii. p. 261. | 
f Botanische Untersuchungen über Schimmelpilze von Dr. Oscar Brefeld. 
_ SECOND SERIES.—BOTANY, VOL. I. - 3L 
