6 BRITISH MARINE ALG. 
rated from its neighbour by a hyaline or colourless space or border. The 
contents of the cells which give to the plants their various hues are termed 
endochrome or chlorophyll, and it is from this colouring matter in con- 
nection with a partial metamorphosis of certain portions of some species 
that the fructification of seaweeds is produced. Of the various forms of 
fructification and other particulars connected with the different systems 
of reproduction I shall speak as occasion arises. Thus much, however, I 
may state at once, that in speaking of the reproductive bodies of some of 
the green plants, the term “ zoospore,”’ in addition to that of spore, will be 
occasionally used, the word zoospore signifying animal seed, from the 
peculiar movements it exhibits in the water by means of the filaments with 
which it is furnished. 
When examined by the microscope, the spores of most of the seaweeds at 
the time of their emission from the cells of the parent plant are found to 
be clothed with very minute hairs, the constant vibratile motion of which 
causes them to move about with the greatest activity. ‘ The little 
spore,”’ says Professor Harvey, “ whilst contained within the mother cell, 
commences life by knocking continually against the walls of the inclosure 
until it has burst through them into the surrounding water, and then with 
many gyrations and rapid changes of place it swims about by means of the 
cilia with which it is clothed, until it finds a substance on which it can 
rest and attach itself. Once fixed, or apparently satisfied with its locality, 
its youthful wanderings are over, and its seemingly yoluntary motions 
cease. The cilia are absorbed or perish, and the vegetable cellule com- 
mences the growth natural to its kind, and finally hecomes a plant 
resembling the species from which it sprang.’? A spore is represented, of 
course very highly magnified, by the little oval figure (Fig, 3) in the group 
of diagrams. . : 
Among the various uses of seaweeds in the economy of nature, especially 
among the green plants, is that of the power they possess, although in a 
small degree, of contributing to the purification of the water in which they 
live. This is due to the oxygen which is generated in their delicate 
tissues, from the carbonic acid which they absorb from the surrounding 
water. Few marine animals will live long healthily in the confinement of 
aquaria, unless the water be properly supplied with growing plants of Ulva 
and other green seaweeds. 
In an interesting little work on British Seaweeds, by the late Dr. Lans- 
borough, I remember reading an account of a rebuff given to an enthusiastic 
young student by a professor of botany, to whom he had shown the contents 
of his vasculum, after a day’s gathering on the sea shore. ‘‘ Pooh, pooh, 
sir,” said the old gentleman, “‘a parcel of seaweeds—pah.”’ Nice encourage- 
ment this must have been for a botanic student, perhaps an incipient 
algologist! This reminds one of the “ Alga projecta vilior’”’ of the old 
Roman poet—terms of contempt for the beauties of the deep, which, I 
suppose, must be forgiven, in consideration for the glorious verses which 
the speaker has bequeathed to us. However, as regards the old professor 
