100 
OF Till-: MARINE ALGAE 
without the object itself giving out sufficient mucous matter 
to allow of its adhering to the stearine cover. 
Up to this point we have had before our eyes only those 
forms of Algas which divaricate into almost infinite ramifi- 
cations. I have treated so largely of them, partly because of 
their overwhelming number, partly on account of the diffi- 
culty involved in preparing them for the herbarium. 
There are, however, numerous other forms, consisting 
mainly of broad flat membranes, thicker or thinner ac- 
cording to the individual species. These are to be simply 
spread out on white paper and laid under the press, any 
folds and wrinkles having been first smoothed down by 
means of a soft hair pencil. There are certain exceedingly 
delicate species (among them may be named the Delesserias, 
several species of Callithamnion, and some of the finer 
Polysiphonias) which do not require any pressure at all. 
Laid upon white paper they dry up in a very short time, 
adhering closely to the surface, and looking, in fact, 
more like a painting or work of art than an object of 
nature. Others, of considerable thickness, should be treated 
after the fashion recommended in chap. vii. for some of the 
fresh-water species. They will adhere readily to the paper, 
and give no trouble in that respect. At the same time, the 
student must notice whether the under- surface of the frond 
exhibits any sort of characteristic clothing. This is the 
case, for instance, with individuals belonging to the genus 
Peyssonelia, in which the lower part of the frond is thickly 
coated with jointed hairs. Where anything of this kind is 
seen to exist, the specimen had better be deposited in a 
paper bag of suitable size, instead of being fixed down, so 
that on being taken out either side of the frond may be 
examined. 
The large Laminarias call for the same kind of treatment 
in its general principles, though varying somewhat to meet 
the exigencies of the case. These giants of marine vege- 
tation are far too large — they often extend to a distance of 
eleven or twelve feet — to allow of their being dried and 
