AIR AS A GERM-CARRIER. 
729 
certain waters rich in organisms the microscopical examina¬ 
tion may be made in a few hours. If the water is compara¬ 
tively pure, twenty-four or forty-eight hours must be allowed 
to pass. The liquid, with the exception of the last one or 
two centimetres, may then be decanted. The detection of 
the organisms in the residue is facilitated by the employ¬ 
ment of colouring* agents, such as Ranvier's picrocarminate, 
methyl violet, logwood, &c. It is always well to introduce 
the colouring agent mixed with glycerine; the organisms are 
thus better tinted, and can, if desired, be better preserved.— 
The Lancet . 
AIR AS A GERM-CARRIER* 
After a long and very unfavorable review of the labours of 
previous aeroscopists, including Pasteur, Lewis, and Douglas 
Cunningham, Dr. Wernich describes certain experiments on 
the action of air-currents upon germs. His apparatus is 
essentially a modification of that previously employed by 
Nageli. Filtered air is drawn through or over the germ-con¬ 
taining material, and thence into a vessel containing pabulum, 
sterilized by boiling. 
He finds ( a ) that thoroughly dried compact masses con¬ 
taining germs, e.g. slices of potato bearing crusts of Micrococci 
and similar incrustations on glass, wire, &c., yield no germs, 
even to the strongest air-current; (b) that coarse and fine 
dust is easily carried over in the stream of air, and the germs 
it may contain develop all the more surely if they are accom¬ 
panied by a small quantity of their former pabulum; (c) that 
porous bodies of different kinds saturated with putrefying 
fluids and then carefully dried, yield germs to the air-stream, 
but slight moistening of the porous body is sufficient to 
prevent this; [cl) that slimy surfaces bearing germs may be 
slightly dried by the current of air and germs then taken up; 
( e ) that germs are not taken up from a fluid through which 
air passes if the formation of spray and foam be guarded 
against. 
The author then discusses the bearing of these results upon 
the ventilation of hospitals, and concludes that while it is 
doubtless important as much as possible to avoid stirring up 
the dust of sick rooms, and to ventilate them by as regular 
and gentle a stream of air as possible, the importance of the 
air as a vehicle of infectious germs has been much exag¬ 
gerated.— Journ . of Hoy. Micro. Society. 
* ‘ Arch. path. Anat. u. Physiol.’ (Virchow), Ixxix, 1880) p. 124. 
