THE SEA-WEED FAMILY. 529 



Uredo Bhinanihaceaarum. On Rhinanthus and Evphrasia. 

 ■ ■ compransor. On leaves of coltsfoot and sowthistle. 



Ruboriim. On bramble leaves. 



Candida. On Capsella, forming oval white blotches. 



CLX.— THE SEA- WEED FAMILY. Alff(B. 



Judging from its English name, the Sea-weed family would be 

 thought to consist only of marine plants, in which case we should 

 here have no concern with it. But there are innumerable species of 

 Algaj found in fresh water, and some are purely terrestrial, occur- 

 ring upon damp ground, and on walls exposed to frequent wet. Of 

 these latter kinds, commonly called Con/ervee, there are plenty near 

 Manchester. Few botanists care, however, to attend to them, nor 

 until 1844 were steps taken in this neighbourhood to ascertain the 

 species and their localities. In that year Mr. Sidebotham commenced 

 the investigation, and during the next four or five summers, Mr. Wil- 

 liamson (now Professor at Owens College), Mr. Thomas Gray, the late 

 amiable John Ashworth, and myself cooperating, those enumerated 

 at foot were determined. Now that a " Manchester Microscopical 

 Society" has been established, it is to be hoped that this interesting 

 branch of botany will receive renewed attention, and that acceptance 

 of the fine opportunities it aflPords for the elucidation of important 

 physiological facts, as well as for delight of the eye, will shew that 

 the members are in earnest. A great deal remains to be done, and 

 the field is alike accessible and rewarding. 



The marine Algae comprise a great variety of forms, from the black 

 and leathery tangles, with their curious bladders, that mantle the 

 clifis, and are stranded in fragments by the retiring waves on the 

 sands of every coast, down to those exquisitely delicate and pellucid 

 rose-coloured species that might be called the ferns and mosses of the 

 sea. The fresh- water species are equally diversified, but none attain 

 such great dimensions. Many of them are only chains of cells or 

 vesicles, of the most beautiful and lucid greens in nature, and a large 

 portion consist of no more than a single cell. The chains are fre- 

 quently as fine as hair, but clustered in such vast numbers as to fill 

 the water with a kind of vegetable cloud. The simplest kinds, called 

 DesmidiecB and Diatomacea, comprise forms so wonderful that when 

 magnified we almost mistrust our eyes. This is not the place to enter 



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