Journal of Proceedings. 
lxvii 
little of this be brought home and placed on a piece of moistened paper, 
in a few hours a brilliant bluish green colour will be found to have 
spread around the central patch. This is due to the fact that the simple 
unbranched threads, each of which constitutes a plant, have the power of 
moving in an oscillating manner, and have thus crept along the paper 
free from the attached mud. From this peculiarity the plants of this 
genus receive the name of Oscillaria. The group to which it belongs is 
also characterised by the possession of a bluish colouring matter, and 
are hence called Cyanophyceas. This colouring matter exhibits a reddish 
tinge when viewed by reflected light. Through the kindness of Mr. 
H. C. Sorby, F.E.S., who has paid considerable attention to the 
colouring matter of plants, I am able to lay a specimen of this sub¬ 
stance before you. Two or three other genera, also belonging to the 
Cyanophyceae, might also be looked for. Of these Lyngbya differs from the 
above chiefly in the plants not having the power of locomotion. Spinilina 
differs from Oscillaria in the threads being twisted like a corkscrew. Beg- 
giatoa is remarkable in this group for the absence of colour, for growing 
on decaying Algae where hydrogen sulphide is given off, and for the 
presence of granules of sulphur in its fronds. No species of this genus 
has been recorded as British, although B. lanugo is almost sure to be 
found if carefully searched for, forming a white fringe on the fronds of 
Geramium rubrum. So far as is known the plants of these genera are 
propagated only by the separation of the contents of the threads into 
portions, each of which can, after leaving the parent frond, develop into a 
new plant. 
“Near high-water mark a number of green, grass-like Algge are sure to 
attract attention, either floating in the pool or attached to rocks or 
stones. On gathering some of these it will be observed that some of the 
threads are branched and others not so ; that some taper towards the 
tips, while others taper towards the base. Those that are unbranched, 
taper towards the base, and consist of a single series of cells, belong 
to the genus Choetomorpha, i.e., bristle-shaped Algas ; while those that 
are branched, and whose threads consist of a single series of cells, belong 
to Cladophora, i.e., branch-bearers. In both these genera the contents of 
distinct cells become metamorphosed into two kinds of zoospores, i.e., 
living spores, so called because by means of cilia they are enabled to move 
through the water, like Infusoria, from which indeed it is difficult some¬ 
times to distinguish them except by their power of becoming attached 
and germinating. The larger zoospores have generally four and the 
smaller two cilia. These are believed to coalesce before germination. 
The genus Enteromorpha often resembles Glaclophora in habit, but under 
the microscope the branches are seen to be composed of a number of 
minute rounded cells irregularly arranged. 
“The genus Ectocarpus resembles Cladophora in consisting of branched 
threads, composed of a single series of cells, but differs in having a brown 
colour, and in the character of the reproductive organs. These are of 
two forms: the one globular, the simple cavity- of which contains ^ 
number of small zoospores ; the other more or less pod-shaped, divided 
into a number of compartments, each of which contains a single large 
zoospore. Both kinds of zoospores have only two cilia. The plants of 
this genus are mostly parasitic on larger Algae, and look like tufts of 
brownish wool when in the water. 
“ The genus Mesogloia comprises a group of brown Algae that are easily 
recognised by their gelatinous, slippery fronds of complex structure. 
Most of the species not found as yet in England grow on the roots or 
old leaves of Zostera. 
“The species of the genus Callithamnion also resemble those of 
