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PROGRESS OF MICROSCOPICAL SCIENCE. 
American Desmids. — ‘Grevillea,’ which is the title of the admirable 
little monthly record of cryptogamic botany issued by Mr. M. C. 
Cooke, M.A., the •well-known fungologist, states that the seven new 
species of Desmids described by Dr. Wood in the ‘ Proceedings of the 
Academy of Natural Sciences,’ at Philadelphia, are named by him — 
Euastrum multilobatum, Euastrum ornatum , Arthrodesmus quadridens, 
Staurastrum minutum, Staurastrum Lewisii, Cosmarium suborbiculare, 
and Pleuroicenium breve. Descriptions in Latin, with measurements, 
will be found in ‘Hedwigia’ for 1872, No. 1, p. 3. 
The Microscopic Action of Quinine and Arsenic. — In a paper read 
before the Biological Section of the Academy of Natural Science, 
America, Dr. Joseph J. Richardson made some important remarks on 
the action of certain medicines in completely removing microscopic 
growths in the skin. He said in conclusion that it is not difficult to 
found a theory for explaining the probable mode of operation of 
quinine and arsenic — so long a problem in therapeutics — when 
acting as tonics upon the human system in many cases of disease : 
namely, that in part, at least, they serve their important purpose by 
rendering the blood less fit for the development of these lower 
organisms, and in this way economizing the supply of nutritive 
material in the circulating fluid. Many well-known peculiarities in 
the action of these two principal tonic medicines tend to confirm such 
a belief — as, for example, the facts : 1st, that quinine and arsenic, two 
substances which, although unlike in almost every other respect, 
resemble each other, as shown by the experiments of Dr. Binz of 
Bonn, and Dr. Dougall, of Glasgow, in being powerfully inimical to 
vegetable life, are in many cases our most reliable tonics. 2nd, that, 
as a general rule, three or four days must elapse before a decided 
invigorating effect is produced upon the system by these remedies — a 
period which, we may conclude, is requisite for sufficiently impreg- 
nating the blood (without disturbing the digestive organs) to render it 
an unfavourable medium for the growth of Bacteria. 3rd, that after 
a continuance of some weeks these roborants generally lose their 
invigorating power upon any particular patient, but seem to have 
regained it if recommenced after their administration has been for a 
short time interrupted — i. e. subsequent to the development of a new 
crop of Bacteria, which they again destroy. And 4th, that arsenious 
acid has so remarkable an effect upon the arsenic-eaters of Styria, 
producing such fat, vigorous, and pure-complexioned individuals when 
steadily continued, and giving rise to such intense suffering if omitted 
for a short time ; results which can hardly be owing to the arsenical 
preparation supplying any necessary constituent of the human body, 
and which seem much more probably to be due to some action in 
preventing a waste of nutriment, and consequently of vital power. 
A Minute Nostoc with Spores. — In Mr. Cooke’s ‘ Grevillea,’ July, 
appears an interesting paper by Mr. W. Archer, of Dublin, on 
