ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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blue. They disappear from the blood six days after the fever has passed 
off, and were never found in persons not sick with influenza. 
Canon has also obtained cultivations of his bacillus from the blood, 
although their small number in the circulation enhances the difficulty 
of this feat. Cultivations were obtained from blood drawn from the 
finger-tip, and made on glycerinized agar and Petri’s capsules. The 
colonies which grew at incubation temperature quite resembled those 
described by Kitasato. 
Differentiation of Leprosy and Tubercle Bacilli.* — It is often im- 
portant for pathological purposes to know whether affections are leprous 
or tubercular. Dr. C. Slater finds that the distinction cannot be learnt 
from an examination of the bacilli, for any colouring agent which 
stains the leprosy bacillus also stains B. tuberculosis; the methods 
proposed to stain B. leprae, while leaving B. tuberculosis unstained, 
are unreliable. Differences have been asserted to exist in the rapidity 
of staining and resistance to decolonization ; but these are due to 
differences in the number of bacilli present. 
We are reminded that stains coming from different manufacturers 
and different samples from the same maker are very variable in their 
staining properties. The two red dyes used by Dr. Slater were a 
magenta obtained from Messrs. Martindale and a rubinfuchsine from 
Konig of Berlin. 
Staining Bacteria in Fatty Substances.f — Dr. C. Arens stains 
bacteria in fatty substrata, e. g. milk, in the following way. 
A loopful of milk and a loopful of distilled water are mixed on 
a cover-glass, dried and fixed by gentle heat. The cover-glass is 
then placed in a watch-glass containing chloroform — methylen-blue made 
by mixing 12-15 drops of a saturated alcohol solution of methylen- 
blue and 3-4 ccm. of chloroform. In this solution the cover-glass is 
moved to and fro for 4 to 6 minutes. The chloroform is then allowed 
to evaporate and the preparation is washed with and examined in 
water. In fresh milk and cream only the bacteria are stained, but if 
curdled the flakes of casein are dyed pale blue, though this does not 
interfere with the distinctness of the deep-blue bacteria. 
Staining Sections of Mosses.! — The cortical and pericyclical zones 
of mosses are composed of cells so much alike that it is difficult to 
distinguish them unless staining agents be used. 
M. Bastit first treats them with a solution of tannin, and, after 
sectioning, with congo red. The tannin acts as a mordant in the cells 
of the pericyclical zone, these being distinguished by their brighter 
colour from the cells of the cortical zone. The sections are next 
placed in a solution of hypochlorite of soda, then of potash, by which 
the cell-contents are removed, and having been rapidly washed, trans- 
ferred to a solution of phosphoric acid. Hereupon they become blue 
but on being immersed in absolute alcohol the stain is removed except 
from the parts which have absorbed the tannin. 
* Quart. Journ. Mior. Sci., xxxiii. (1891) pp. 219-28. 
f Centralbl. f. Bakteriol. u. Parasitenk., xi. (1892) p. 10. 
j Kev. Ge'n. de Dot., iii. (1891) p. 432. 
