84 
NOTES AND MEMORANDA. 
to Schwarz, who advised the mixing of picric acid with carmine in 
studying the unstriated muscles of the intestines, or to the picro-car- 
minate of Eanvier, now so well known. I may add also that it has 
been suggested that a green stain might be obtained with picrie acid 
dissolved in glycerine by the addition of a certain quantity of a 
decoction of logwood and the neutral chromate of potash, in the 
proportion of 1 part to 1000. 
I avail myself, however, of picric acid mixed with soluble aniline 
blue to obtain a green tint of considerable delicacy, homogeneous as far 
as the eye can detect, and which serves to bring out in relief the smallest 
details which are presented by the tissues and their elements. This 
green stain is easily obtained, in a comparatively short time, either by 
subjecting the preparation to bo stained to a solution in water of 
soluble aniline and picric acid, or first to a solution of aniline and 
then to another of picric acid. In whichever way these colouring 
matters are employed, an effect is obtained equally quick and satis- 
factory. The solutions, whether of picric acid or aniline, ought to be 
saturated, which can be done without difficulty by leaving an excess 
of each substance at the bottom of the vessels in which the materials 
are placed to dissolve. In this way we are always sure of employing 
only saturated solutions. When it is wished to make use of the picro- 
aniline solution, 100 cubic centimetres, for example, should be taken 
of the saturated aqueous solution of picric acid, and into it should be 
poured 4 or 5 cubic centim. of the blue liquid also saturated. The 
resulting solution admirably stains a preparation of the lymphatic 
glandular system in the space of a few minutes. If it is desired 
to employ the two substances separately, keep the preparation in the 
aniline solution for a few minutes, and afterwards place it in the 
picric acid. In working thus we can see that the preparation is not 
stained too much by the aniline, and to this end it is well to take it 
out as soon as it has acquired a light sky-blue tint. By taking it out 
at this point one is always sure that it will show the nuclear 
elements sufficiently coloured, whilst the protoplasmic parts and 
others will be only very slightly stained. By waiting, on the con- 
trary, till the preparation has taken a dark blue tint, the nuclei will 
be very deeply stained and the other parts rather deeply also, so 
much so that on submitting it afterwards to the staining action of the 
picric acid it becomes confused and obscure. The preparations which 
have been treated with the aniline solution, with the precautions 
indicated above, and then placed in picric acid, pass in the course of 
about fifteen minutes from sky blue to a delicate green. After this 
treatment the tissues show the nuclei both free and cellular suffi- 
ciently stained with green, the protoplasm and the fibres coloured 
pea-green, though faintly and with a delicate shade. Since the 
staining by the aniline produced by the first treatment was less 
in these parts, the yellow colour predominates over the blue, whence 
there results a lighter and more delicate tint. 
Similar results are obtained by making a picro-aniline solution act 
on the different tissues. It is possible to stain with groat advantage 
not only fresh tissues, but also such as have been subjected to the action 
