ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
901 
3 minutes. The preparation may then be contrast stained or examined 
at once in water, the tubercle bacillus appearing dark-red on a whitish- 
grey background. 
In order that the staining should succeed well, the layer of sputum 
should be as thin and even as possible. 
Fabre-Domergue — N ote a propos de la methode bacteriologique an bleu de 
prusse de M. Solles. (Note on M. Solles’ Method of staining Bacteria with 
Prussian Blue.) Compt. Rend. Soc . Biol., 1892, p. 407. 
Moore, Y. A. — Observation on Staining the Flagella on Mobile Bacteria. 
Bacteriol. World, Battle Creek, Midi., 1891-92, pp. 115-9. 
Solles — M ethode nouvelle de recherche bacteriologique ; ses premieres applica- 
tions. (New Method of Bacteriological Research ; its first applications.) 
Journ. Med. Bordeaux, 1891-92, pp. 258-9. 
Squire, P. W. — Methods and Formulae used in the Preparation of Animal and 
Vegetable Tissues for Microscopical Examination, including the Staining of 
Bacteria. London, 1892, 8vo, 100 pp. 
Straus, J. — Sur un procede de coloration a l’etat vivant des cils ou flagella de 
certaines bacteries mobiles. (On a Process for Staining in the Living State the 
Cilia or Flagella of certain Mobile Bacteria.) 
Compt. Rend. Soc. Biol., 1892, pp. 542-3. 
W u r tz — T echnique Bacteriologique. (Bacteriological Technique.) 
Paris, 1892, 8vo. 
C 5) Mounting-, including- Slides, Preservative Fluids, &c- 
Use of a Substitute for Canada Balsam.* — Dr. A. M. Edwards, 
who has long sought for a substitute for Canada balsam for mounting 
objects for microscopic use, and has, in fact, employed a hundred 
different media, rejected them one by one until he got the one which 
he now describes. 
“ I use the gum thus, or frankincense, which is the gum or balsam of 
the Finus tseda L. (loblolly, or old field pine), which is found in Virginia 
and southward, common. In Florida it is very common, constituting tho 
‘ Pine Barrens ’ of that State. It was described in the ‘ Dispensatory 
of the United States of America,’ sixteenth edition, 1889, by Wood and 
Bache, and by Wood, Remington, and Sadtler as from the Firms 
Australis Mich. (P. palustris Mill.), and P. tseda Linn. It is dissolved 
in alcohol. A saturated solution is made by adding ordinary alcohol to a 
large quantity of the gum and set by for a day or so until it is dissolved. 
The clear solution, which is darker than balsam, is poured off, and three 
parts acid to one of oil of cinnamon is added to nine [parts of the solu- 
tion]. This is the solution that is used for mounting. The gum thus is 
more highly refractive than Canada balsam alone, and when we add to 
it oil of cinnamon we use liquid of the highest refractive powers that we 
can use. To use it, we dry the substance, diatoms, or other substance 
in the cover or slide, and add with a dipper (an iron wire is good) a 
drop or two of the solution. We then warm it until the alcohol is flown 
off and bubbles formed are driven off, and the cover is pressed on the 
glass slide and the whole cooled. The slide is then cleaned with solu- 
tion of ammonia (I use a weak household ammonia) or carbonate of 
soda, or borax and water. A ring of asphaltum or gold size can then 
* Science Gossip, 1892, p. 236. 
