236 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
oils, in xylol, and in boiling acetic acid. It is extremely soluble in 
sulphuric acid, but then turns a dark-green colour. It has long been 
employed as a stain for animal fat. The author has examined its re- 
actions towards vegetable tissues, and states that it is excellent for cutin, 
suberin, resin, and wax, which it stains a deep red. Cellulose mem- 
branes, collenchyme, and mucous membranes are unaffected. Woody 
tissues either do not stain or assume a blue-violet hue, and occasionally 
(Orchidese) a faint red. The contents of cells, nuclei, protoplasm, 
starch-granules, and tannin do not stain ; but oil, resin, and the contents 
of laticiferous vessels stain bright red. Chlorophyll-grains are stained 
a faint red, though certain minute granules within the grains are deeply 
coloured ( Cycas , &c.). The reaction to spore-membranes and pollen 
grains is variable. 
Sudan iii. may be used alone or in conjunction with eau de Javelle. 
Preparations are permanent. 
New Stain for Tubercle Bacilli.* — Dr. M. Dorset has discovered 
that Sudan iii. is a good stain for tubercle bacilli. The preparations, 
films, or sections are first treated with 80 per cent, alcoholic solution of 
Sudan iii. for 5 or more minutes ; the excess of stain is removed with 
70 per cent, alcohol, and the preparations contrast stained, if necessary, 
with methylen-blue. 
Sudan iii. appears to be quite a specific and selective stain for tubercle 
bacilli. Even when smegma and tubercle bacilli are mixed together, 
the new stain picks out only the tubercle bacilli. 
Method for Ripening Hsematoxylin.j — Prof. H. F. Harris pre- 
pares a ripened solution of haematoxylin as follows. 1 grm. of hema- 
toxylin crystals is dissolved in 10 grm. of absolute alcohol. 20 grm. 
of ammonium or potassium alum are dissolved by the aid of heat in 
200 ccm. of distilled water. The two solutions are mixed at once or 
after 24 hours, and 0’5 grm. of mercuric (red or yellow) oxide is 
added ; the mixture is heated to boiling and then quickly cooled. 
The liquid at once assumes a dark-red colour, and may be at once 
used for staining. Sometimes a precipitate occurs after a few days, 
but after filtration does not re-form to any extent. On account of its 
reducing property chloral was added to some of the staining fluid ; after 
a year this was found to be free from precipitate. 
Method for Staining Secondary Degeneration in Nervous System.^: 
— The most important defect of Marchi’s method, says Herr Ch. K. 
Busch, is associated with the slight penetrating power of osmic acid, 
which often does not reach the deeper layers. This defect may be 
remedied by diluting the osmic acid solution with a solution of iodate 
of soda, which prevents the osmic acid from decomposing too quickly, 
and permits it to penetrate into the tissue. A preparation (1 # 12 cm. 
thick) hardened in formol is placed in a mixture of osmic acid 1, 
sodium iodate 3, distilled water 300, for 5 to 7 days ; then alcohol of 
increasing strength. 
* New York Med. Journ., lxix. (1899) pp. 148-9 (1 pi.). 
t Micr. Bull., xv. (1898) p. 47. 
% Neurol. Centralbl., xvii. (1898) p. 476. See Zeitschr. f. wiss. Mikr., xv. (1899) 
p. 373. 
