100 OF THE MARINE ALGjE. 



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 Algae 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 Delesseria?, 

 several species of Callithamnion, and some of the finer 

 Polysiphonia?) 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 Laminarise 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 



