66 
OF THE FILAMENTOUS ALGJS. 
inhabiting quickly-flowing streams. In most cases (es* 
pecially with the species of Cladophora) the plant must 
be gathered as near the point of attachment as possible — 
the point, that is, corresponding to the root in a flowering 
plant ; for, since the determination of the species depends 
in great measure on the position of the main stem, its 
degree of ramification, &c., it is by no means a matter of 
indifference whether the whole plant or a mere fragment 
be secured. This precaution is not so necessary with the 
Ulothricacese, as they consist of unbranched filaments. On 
that very account they should be carefully collected with 
the hand, not with the ladle, and then laid lengthways on 
a strip of paper so as not to disturb the filaments, which 
adhere but loosely together, and are easily separated and 
carried away by the draining off of the water. 
If the tufts (as is often the case with the Vaucheria}) are 
dirty and discoloured, the mud and sand must of course 
be washed off before the specimens are prepared for the 
herbarium. They had better, however, be carried home 
first, and thoroughly examined for DiatomaceEe. It will 
be time enough then to cleanse away impurities, taking 
pains during the operation to avoid entangling the fila- 
ments, and to preserve the natural habit of the plant. 
All the filamentous Algse may be laid out for ultimate 
preservation on stout writing paper. The size of the 
paper may be proportioned to the length of the object to 
be laid on it. In practice, however, I have found the most 
convenient form to be as follows : Let a half sheet of 
writing paper be cut longitudinally into three strips, and 
let each of these be again divided across the centre. A 
sheet of paper will then give twelve portions, each of 
which is of such a size as to lie comfortably on the palm of 
the hand. The plants having been well cleaned from 
fallen leaves, twigs, decayed matter, &c., and divided into 
several distinct portions, are allowed to spread themselves 
out on the surface of water in a large dish. One of the 
portions is now taken out and made to float in another 
