The razor should always be dipped in spirit first, and the sections 
eut obliquely towards the operator. The tissue having been 
hardened, and the sections cut, we have next to consider the most 
advantageous way of exhibiting them under the microscope, and for 
this, in most cases, they must be stained. The chromic acid, as I 
have before said, itself stains sufficiently for mounting in glycerine; 
but it has the disadvantage of colouring all parts alike. The nuclei, 
the cells, and the stroma, are all of the same pale yellowish-brown. 
Nevertheless, very good specimens may be obtained by simply 
mounting chromic acid sections at once in glycerine, and many 
microscopists still adhere to this method. If, however, as I re- 
commend you to do, you take the additional trouble of a further 
staining, you must, in the first place, select a colouring fluid. 
There are many open to choice, none, perhaps, more beautiful than 
_ the aniline dyes, yet none that you will do better to avoid, for they 
soon fade, and what might otherwise have been a valuable specimen 
- is irretrievably lost. Of the others, I would recommend a selection 
to be made from carmine, logwood, or some inks, as Field’s 
chemical ink, or Stephen’s blue-black writing fluid, and of these I 
3 usually employ logwood.- The application of gold and silver to 
staining purposes T shall refer to presently. Of the carmine fluids 
_ there are two forms in use; Beale’s, which is made up with gly- 
cerine, and the aqueous solution, recommended by Klein. They 
are too well known for it to be necessary for me to repeat the 
formule. The logwood fluid is usually prepared after the manner 
recommended by Dr. Green, of Charing Cross, in his Pathology, 
- namely, by triturating the extract of logwood in a mortar, with an 
excess of alum and water, and subsequently adding a little rectified 
spirit to keep it. But I prefer to prepare it by dissolving the 
y colouring matter contained in a drachm of powdered extract of log- 
- wood in two ounces of water, to which two or three drachms a 
- dilute hydrochloric acid have been added. This is then filtered 
into about half-a-pint of water, and liquor ammonia is added until 
a thick purple precipitate forms, which is re-dissolved by shaking 
up with alum. A little spirit may then be added to preserve it. 
_ The inks mentioned stain many tissues well, and require nothing 
more than dilution in water. Well, to return to the sections. As 
1ey are cut, they are washed off the razor with a paint brush 
pped in methylated spirit into a watch-glass, until about a couple 
of dozen have collected. From these the best are picked out and 
transferred to the staining fluid with a needle in a handle, or a 
small paint brush; I prefer the former since it carries less fluid. 
As to the strength of the staining fluid, that I think can only be 
ertained by experience, since it depends upon the number of 
ions as well as the quantity of fluid used. One must be guided 
chiefly by the time taken to stain sufficientiy, which should not be 
Jess than 12 hours; for in rapid staining all the elements of the 
