lxviii
Journal of Proceedings.
Cladophora in structure, but are of a red or pink colour, and have much
more highly developed reproductive organs. These consist of an organ
resembling the pistil of flowering plants, which is fertilised by antheridia,
and subsequently results in a double mass of spores enclosed in a thin
membrane. The antheridia occur in rounded tufts, taking the place of a
branchlet. Besides these organs some of the branchlets are replaced by
oval bodies called tetraspores, and which may be considered analogous to
the deciduous buds of flowering plants and ferns, since they can reproduce
the species without fertilisation. There are three forms of tetraspores in
different genera of the Red Alga?, but in the Callithamnia they are usually
tripartite or cruciate. The plants of this genus form small pink tufts
on other Algae, or grow on mud or on the muddy sides of quays at very
low water.
" The Polysiphonia differs from the Callithamnia in the threads of the
fronds being compound, each joint containing four or more tubes or
siphons. The female flower, if it may be so called, results after fertilisa-
tion in a capsule containing a number of spores, and the colourless
antheridia are sausage-shaped and attached to the tips of the fronds,
giving them a yellowish appearance. The tetraspores are formed inside
the terminal branchlets. These plants are found chiefly on rocks and
stones or muddy shores, and some of the species are of very limited
duration.
"In conclusion, I may add that the most likely places to prove prolific in
new British species are brackish ditches near the sea, mill-pools con-
taining sea water, estuaries, muddy and sandy creeks where the water
flows in slowly, and Zostera beds. Shells and larger Algae brought up
by the dredge are also worth examination. Of many microscopical
species the life history is very imperfectly known, and would well repay
careful study. The influence of sex, of fresh water, and of rough and
still water in controlling the shape and appearance of Marine Alga; are
points that require further investigation."
Mr. C. B. Plowright, M.R.C.S., of King's Lynn, gave {viva voce) a
highly graphic and amusing summary of his recent researches upon
the reproduction of the Uredines, a group of Fungi, comprising the
rusts and mildews of cereals, which furnish some of the most striking
illustrations of the phenomena of " cyclical propagation" among
plants. Mr. Plowright confined himself to the history of the develop-
ment of the corn-mildew or "rust" (Puccinia graminis), tracing its
connection with the Barberry Fungus (AEcidium berberidis), illus-
trating the subject with some clearly-drawn diagrams and specimens.
Mr. Plowright's remarks will not bear condensation, but his valuable
results will be found recorded, together with a history of the litera-
ture of the theory of heteraecism in this group of Fungi, in his
various papers in ' Grevillea,' ' Gardeners' Chronicle,' ' Science
Gossip,' and the 'Transactions of the Woolhope Club' during the
years 1881 and 1883. All these papers may be consulted in the
Library of the Club, and the whole subject possesses great interest
to dwellers in the country having microscopes, and endowed with
the skill and perseverance necessary to follow in Mr. Plowright's
footsteps.
Mr. Worthington G. Smith, F.L.S., then read the following paper,