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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Neutral Red.* * * § — According to Prof. Ehrlich this new pigment, 
neutral red, is excellently adapted for biological researches and vital 
staining, as it possesses a striking affinity for living tissues. If tadpoles 
be placed in solutions of 1-10,000 up to 100,000 the animals become 
stained in quite a short time, and during the first and second day of their 
immersion absorb so much of the pigment that all their tissues become 
dark red. The pigment may be seen in the cells as minute granules. 
Larger animals may be subcutaneously injected, and even feeding with 
the pigment gives good results. In germinating plants the author 
obtained successful staining results, and by combination with other 
pigments, e. g. methylen-blue, &c. a double or triple staining. 
Demonstration of the Presence of Iron in Granules of Eosino- 
phile-Leucocytes.j — Dr. L. F. Barker, after noticing Dr. A. B. 
Macallum’s t method for the demonstration of iron in chromatin, gives 
the following account of his own method for the micro-chemical demon- 
stration of iron. “ In my experiments cover-glass preparations, such as 
are employed for the colour analysis of the leucocytes according to the 
methods of Ehrlich, were heated on the copper bar at a temperature of 
120° C. for from one to two hours, and were then treated in the following 
way : — A drop of solution of ammonium sulphide, prepared just before 
using, was placed upon the smeared surface of the cover-slip, and this 
was immediately laid upon a drop of glycerin, the glycerin and sul- 
phide solution mixing, upon a large thick glass slide. The preparation 
was then placed in the thermostat at 60° C. Once as early as after 
6 hours, but usually at the end of 24 hours, and more markedly at the end 
of 48 hours, the greenish-black iron reaction in chromatin of the nuclei 
of the white corpuscles was apparent in the specimens. By this time 
the haemoglobin of the red corpuscles had assumed only a slight greenish 
tint. In an occasional leucocyte, however, granules of the size and shape 
of the eosinophile granules were very distinctly stained yellowish-green. 
To make sure that the granules were really those of the eosinophile 
leucocytes (although the morphology of these granules is in itself so 
typical that they can, as a rule, be recognized in fresh unstained speci- 
mens of blood), some cover-slip preparations, known by control-studies 
of slides stained with the triple stain to contain a much larger number of 
eosinophile leucocytes than normal, were submitted to the same test. In 
these too, the eosinophile granules stained sharply. The blood taken 
from a patient whose blood contained 18 per cent, of eosinophiles yielded 
very striking pictures. 
The granules in the sulphide-glycerin preparations do not assume 
quite the same tint as do the nuclei of the leucocytes ; the latter are 
stained greenish-black and have a dull appearance. The eosinophile 
granules, by contrast, are more highly refractive, and while stained 
greenish-black show also a slight yellowish tint. 
Osmic-Iron-Haematoxylin Staining Method. § — Dr. Kaiser treats 
the central nervous system in the following way : — The pieces are placed 
* Allgem. Med. Centralzeit., 1894, p. 20. See Zeitschr. f. wiss. Mikr., xi. (1894) 
p. 250. t Bull. Johns Hopkins Hospital, v. (1894) p. 93. 
I Proc. Roy. Soc., 1. (1892) pp. 277-86. See also this Journal, 1891, pp. 82-9. 
§ Neurol. Centralbl., xii. (1893) pp. 363-4. See Zeitschr. f. wiss. Mikr., xi. 
(1894) pp. 249-50. 
