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POPULAR SCIENCE REVIEW. 
Grahamstown, and lias been identified by Dr. F. Mueller, of Melbourne. 
The species is styled S. tropceolifolius. Dr. Mueller, in commenting on this 
discovery, makes the following very interesting remarks on the geographi- 
cal distribution of the genus : — Senecio is not merely more widely distributed 
over the globe than any other existing genus, from the polar to the equinoctial 
regions of both hemispheres (though almost absent in North Australia), but it 
embraces more species than any other — nearly a thousand being on record, some, 
however, but ill- defined. The genus almost as rich in species, and almost as 
extensively diffused, is Solarium, and then seemingly follow Panicum , Carex, 
and Euphorbia, though in Australia Acacia largely surpasses all others. The 
species of Senecio , as representatives from almost every part of the globe, 
become thus of the greatest possible interest, and are certain to be always 
among the first which come under the notice of any photographical observer. 
The Groundsels, though generally of the more humble forms of vegetation, 
present, in a recently discovered species from the Chatham Islands ( Senecio 
Huntii: “Vegetation of the Chatham Islands, sketched by F. M., p. 23, 
plate 3) ; and in the Victorian and Tasmanian S. Bedfordii (F. M., Deport, 
1868, p. 26), fair-sized trees, perhaps the only truly arborescent species of the 
globe. 
The Arctic Cladonice. — On this group of plants an essay, which we hope 
to see printed in full, was read before the Botanical Society of Edinburgh, 
by Dr. W. Lauder Lindsay. The Arctic regions include vast level, generally 
treeless, barren tracts of country, whose vegetation is frequently exclusively 
lichenose ; sometimes, indeed, consisting of a single species, the cosmopolite 
Cladonia rangiferina. The author enumerates the different species and their 
forms, belonging to the Cladonice, found in Arctic countries, and remarked 
that, whether these may be regarded as consisting of many or few species, 
their importance to man cannot be estimated by their mere numerical rela- 
tions ; one species at least (C. rangiferina) is not only superior in economical 
and even political importance to the better- known u Orchella-weed,” but it 
is even on a footing with the valuable grains, timber trees, and other 
phanerogams of more favoured regions. The author considered the econo- 
mical value and applications of the Arctic Cladonice under the following 
heads : — 1, as fodder or forage to animals, domesticated or wild ; 2, as an 
ingredient of man’s food ; 3, as medicines, being used as tonics, astringents, 
febrifuges, emetics ; 4, in the arts — e. g., perfumery and dyeing. 
The Parasites of a Desmid. — Mr. W. Archer, who is one of our most 
industrious students of microscopic Algae, records that he has found 
Asteridia parasitic in the common Desmid, Penium digitus. In a collection 
containing a number of the Penium digitus, Mr. Archer observed that a 
considerable number of them showed “ some individuals one, the majority 
two, and a few three, quite identical stellate bodies in the interior of each 
cell.” These seemed to him evidently to have been formed at the expense 
of the individual Penium in which they occurred. These stellate bodies Mr. 
Archer identifies as the Asteridia. He lays down the following general 
propositions in concluding his paper : — (1) The strictly parasitic nature of the 
Asteridia seems probable, from the destruction of the Penium during their 
formation ; (2) The observation is of interest as being the first record of the 
occurrence of “ Asteridia ” in Desmids ; and (3) from their being of a form 
and size not before noted in any of the Asteridia recorded. 
