Fungi: Their Nature and UsesCooke, M. C. (Mordecai Cubitt)
Science
Fungi: Their Nature and Uses
Cooke, M. C. (Mordecai Cubitt)
Fungi
In _Puccinia_, as already observed when describing their structure,
the pseudospores are two-celled. From the pores of each cell, which
are near the central septum, springs a clavate tube, which attains two
or three times the total length of the fruit, and of which the very
obtuse extremity curves more or less in the manner of a crozier.[G]
This tube, making a perfectly uncoloured transparent membrane, is
filled with a granular and very pale plastic matter at the expense
of the generative cell, which is soon rendered vacant; then it
gives rise to four spicules, usually on the same side, and at the
summit of these produces a reniform cellule. The four sporules so
engendered exhaust all the protoplasm at first contained in the
generative cell, so that their united capacity proves to be evidently
much insufficient to contain it, the more so as it leads to the
belief that this matter undergoes as it condenses an elaboration
which diminishes its size. In all cases the spicule originates
before the sporule which it carries, and also attains its full length
when the sporule appears. The form of the latter is at first
globular, then ellipsoid, and more or less curved. All these phases
of vegetation are accomplished in less than twelve hours, and if
the spore is mature and ready for germination, it is sufficient to
provoke it by keeping the pseudospores in a humid atmosphere.
During this process the two cells do not separate, nor does one
commence germination before the other, but both simultaneously.
When the sporules are produced, the protospore, somewhat analogous
to a prothallus, has performed its functions and decays. Towards
the time of the falling of the sporules they are nearly all divided
into four unequal cells by transverse and parallel septa. These
sporules in time produce, from any point on their surface, a
filament, which reproduces a new sporule, resembling the first, but
generally smaller. This sporule of the second generation ordinarily
detaches itself from its support before germinating.
[Illustration: FIG. 85.--Germinating pseudospore of _Puccinia Moliniæ_.
(Tulasne.)]
[Illustration: FIG. 86.--Germinating pseudospore of _Triphragmium
ulmariæ_ (Tulasne.)]
The pseudospores of _Triphragmium ulmariæ_ have been seen in April
germinating on old leaves of the meadowsweet which survived the
winter, whilst at the same time new tufts of the spores were being
developed on the leaves of the year. These fruits of the spring
vegetation would not germinate the same year. Each cell in germination
emits a long cylindrical filament, containing a brownish protoplasm,
on which four spicules, bearing as many sporules, are generated.
[Illustration: FIG. 87.--Germinating pseudospore of _Phragmidium
bulbosum_. (Tulasne.)]
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