758 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
as the crystals are sometimes very difficult to remove. The author 
condemns the inferences drawn by many investigators of carcinomata in 
organs, chiefly on the ground that their results have been obtained by 
using fixatives which do not preserve spores well, and which produce 
curious artefacts in the stained spores, distorted by the fixing fluids. 
Zenker's Fixative.* * * § — Dr. K. Zenker recommends as a fixative the 
following solution : — Distilled water 100*0, sublimate 5*0, bichromate 
of potash 2*5, sulphate of soda 1*0, acetic acid 5*0. Though the 
solution keeps well, it is better to add the acetic acid shortly before 
using it. Pieces 1 cm. thick are perfectly hard in less than 24 hours. 
The after treatment consists in washing well in running water, and then 
dehydrating in alcohols of increasing strength. If any sublimate re- 
main it may be removed either from the piece or from the sections by 
means of iodine alcohol. No distortion occurs during the after-harden- 
ing in spirit. The sections stain well. 
Formol as a Preservative Fluid.f — Herr J. Blum is strongly im- 
pressed with the value of formol as a preservative fluid. Formol is a 
40 per cent, solution of formaldehyde, and comparatively recently has 
come much into vogue for preserving museum specimens for microsco- 
pical and also for bacteriological work. Animals hardened in formol 
preserve to a great extent their natural form and colour ; their eyes are 
clearer than in spirit. Mucin is not coagulated, and retains its trans- 
parency. Blood colouring matter of tissues and organs placed in formol 
apparently disappears, but on immersing the object in not too weak 
spirit (6(3-90 per cent.) the characteristic colour is restored. Vege- 
table tissues and structures are also well preserved in formol. Chloro- 
phyll is not extracted, though it appears to undergo some change, which 
varies with the plant. Microscopical sections of plants preserved in 
formol give excellent pictures. Diluted formol does not burn, and is 
cheaper than alcohol. 
Pacini’s Preserving Fluid.f — Prof. A. Lustig has examined cholera 
dejecta which had been kept in Pacini’s fluid since 1831. The fluid 
consists of mercury chloride 1, sodium chloride 2, distilled water 200. 
The composition of the mixture was in Pacini’s own writing. 
Microscopical examination of the yellowish-white sticky mass at the 
bottom of the vessel showed that the organisms were well j)reserved, the 
predominating form being a curved bacillus, with thin rounded ends, 
about the length and thickness of the comma bacillus. Stained cover- 
glass preparations were also very good. The author points out that 
this fluid must be an excellent medium for preserving material for 
microscopical examination. 
Fixing Methods and the Granula.§ — Dr. A. Fischer has some 
criticism of fixing methods. Chromic acid ( * 5 per cent.), osmium acid 
(1 per cent.), Altmann’s mixture of 1 per cent, osmic acid and 2 * 5 per 
cent, bichromate of potassium and other fixatives cause solutions of 
* Miinchener Med. Wocliensckr., 1894, No. 27. See Centralbl. f. Bakteriol. u. 
Parasitenk., xvi. (1894) pp. 542-3. 
t Bericht Senkenbergische Naturf. Gesell., 1894, pp. 195-204. 
t Centralbl. f. Bakteriol. u. Parasitenk., xvi. (1894) pp. 326-8. 
§ Anat. Anzeig., ix. (1894) pp. 678-80. 
