288 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
The blood on the cover-glass may be exposed to the action of the 
vapour, or the acid (1 per cent, solution) may be mixed with it thereon, 
or it may be dropped into a watch-glass full of the acid. If the last 
method be adopted, the procedure may further be improved and simpli- 
fied by mixing some pigment with it, so that the blood is at once stained 
and fixed. For this purpose the most useful dyes are methyl-green, 
methyl-violet, crystal violet, safranin, eosin, acid fuchsin, and rho- 
danin. In all cases a saturated aqueous solution of the pigment is 
mixed with a 1 per cent, solution of osmic acid. 
For fixing and imparting a double stain good results were obtained 
from rhodanin and methyl-green. These pigments are to be dis- 
solved separately and then added to the osmic acid. A blue-red fluid 
results, which stains the cell-body red and the nucleus green. Besides 
csmic acid, picrosulphuric acid, clirom-osmium-acetic acid, and gold 
chloride are favourably alluded to as fixatives. 
For preserving specimens of fixed molluscan blood, resinous media 
are not suitable, the best material for the purpose being glycerin, which 
mixes easily with the before-mentioned fluids, and also keeps the colour 
fairly well. Permanent preparations are made by running a thin border 
to the cover-glass with some oil-colour (Cremser white), so as to prevent 
any pressure on the cell-elements, and also to keep the glycerin from 
exuding. Some glycerin is placed on the middle of the cover-glass, and 
to this is added the mixture of the blood and fixative and the whole 
carefully mixed. The cover-glass is then carefully laid upon a slide 
and ringed round. 
Staining Terminations of Tracheae and Nerves in Insect Wing 
Muscles by Golgi’s Method.* — By the application of Golgi’s method 
to the muscles of insects, Prof. S. R. Cajal obtained some unexpected 
results. It was found that the tracheae in the feet and wings (the non- 
dissociable muscles) terminate in two horizontal networks, while in the 
dissociable muscles only one such network was demonstrable. The 
method also showed the termination of the nerves in the muscle-fibres 
as a system of delicate filaments, some of w r hich were disposed upon 
and others beneath the sarcolemma. The technique is as follows : — 
Pieces 3-4 mm. thick are cut from the wing muscles and immersed for 
12-24 hours in a mixture of osmic acid and potassium bichromate 
(1 per cent, osmic acid 5 parts, 3 per cent, bichromate of potash 20 
parts). They are next placed for 24 hours in 0*75 per cent, nitrate of 
silver solution, after which they are treated with 40 per cent, alcohol. 
Thus prepared, the pieces are teased out and then again washed several 
times in spirit ; after this they are cleared up in oil of cloves, passed 
through oil of turpentine, and then mounted in the usual way. For 
obtaining transverse sections, the muscle may be placed in elder- 
pith and so cut up, or it may be imbedded in paraffin and sectioned. 
The black reaction in the tracheae is always constant, but the staining 
of the nervous tissue is less certain, so that it is advisable to make a 
good number of preparations. 
* Zeitsehr. f. Wiss. Mikr., vii. (1890) pp. 332-42 (1 pi. and 3 figs.). 
