Fungi: Their Nature and UsesCooke, M. C. (Mordecai Cubitt)
Science
Fungi: Their Nature and Uses
Cooke, M. C. (Mordecai Cubitt)
Fungi
There are often also a certain number of the branches which had
acquired a clavate shape, and do not erect themselves above the
surface, instead of producing a fertile thread, which would seem to
have been their first intention, become abruptly attenuated, and are
merely prolonged into a mycelial filament. Although in other species
chlamydospores are formed in such places on the mycelium, nothing of
the kind has been traced in this species, more than here indicated.
Occasionally, when germination is arrested prematurely, certain
portions of the hyphæ, in which the protoplasm maintains its vitality,
become partitioned off. This may be interpreted as a tendency towards
the formation of chlamydospores, but there is no condensation of
protoplasm, or investiture with a special membrane. Later on this
isolated protoplasm is gradually altered, separating into somewhat
regular ovoid or fusiform granules, which have, to a certain extent,
the appearance of spores in an ascus, but they seem to be incapable of
germination.
Another method of reproduction, not uncommon in _Mucorini_, is
described by Van Tieghem in this species. Conjugating threads on the
substratum by degrees elaborate zygospores, but these, contrary to
the mode in other species, are surrounded by curious branched
processes which emanate from the arcuate cells on either side of the
newly-developed zygospore. This system of reproduction is again
noticed more in detail in the chapter on polymorphism.
M. de Seynes has given the details of his examination of the sporidia
of _Morchella esculenta_ during germination.[O] A number of these
sporidia, placed in water in the morning, presented, at nine o'clock
of the same evening, a sprout from one of the extremities, measuring
half the length of the spore. In the morning of the next day this
sprout had augmented, and become a filament three or four times as
long. The next day these elongated filaments exhibited some transverse
divisions and some ramifications. On the third day, the germination
being more advanced, many more of the sporidia were as completely
changed, and presented, in consequence of the elongation, the
appearance of a cylindrical ruffle, the cellular prolongations arising
from the germination having a tendency towards one of the extremities
of the longer axis of the sporidium, and more often to the two opposed
extremities, either simultaneously or successively. Out of many
hundreds of sporidia examined during germination, he had only seen a
very few exceptions to this rule, among which he had encountered the
centrifugal tendency to vegetate by two opposed filaments, proving
that if it bears a second by the side of the primal filament situated
at one of the poles, a second would also be seen from the side of the
filament coming from the opposite pole.
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