Preparing and Staining Fresh Brain, &c. By Bevan Lewis. 109 
balsam in lieu of chloroform, bat judging from the results obtained 
I find the plan advised preferable. 
In reviewing briefly the process now described it will be seen 
that the prepiration of the film is a feature of most essential im- 
portance, and it will be readily understood that the employment of 
Miiller's fluid can prove in no way detrimental to the delicate 
cellular apparatus with which we are dealing. This fluid medium 
has been, I believe, very universally acknowledged by most histo- 
logists as the best for the preservation of the most delicate nervous 
textures, such as the retina, &c., with the least possible alteration of 
textural relationships. By its means, also, we avoid the extreme 
friability which a film produced in water alone acquires, and at the 
saDie time we reduce to a minimum that adhesiveness natural to a 
thin lamella obtained from the brain by pressure, and hence render 
the removal of the cover-glass a matter of the greatest simplicity. 
The subsequent short treatment by spirit still further aids the last- 
mentioned object, and serves to free the film rapidly from all traces 
of the bichromate. Thus, then, is our primary object attained in 
the formation of a delicate lamella of the cortex, and the safe re- 
moval of the covering glass. Once this is obtained, we need no 
longer fear the friability induced by endosmose of water, and which 
would have been fatal to our object if induced prior to removal of 
the cover. The subsequent removal of spirit is found essential to 
a perfect and rapid staining by the aqueous solutions of aniline, and 
the further steps of the process explain themselves, I believe, too 
readily to our minds to need any further comment upon. 
Those who have attempted the staining of fresh as well as 
hardened brain will readily allow that the dye acts far more 
energetically and with more favourable results in the former than 
in the latter case, and diff'erentiation is ensured by the absence of 
that diffuse staining which so often complicates matters in the pre- 
paration of sections obtained from brain hardened by chromic acid. 
The idea therefore occurred to my mind that if hardening by chromic 
acid and its salts acts thus detrimentally in the subsequent staining 
process, could we not devise a method whereby the staining might 
be completed ere this unfavourable effect upon the germinal centres 
took place ? I believe I have solved this question satisfactorily, for 
I find that staining of a most perfect character may be induced 
during the subjection of fresh brain to certain hardening reagents. 
Some of the best carmine preparations of the cortex which I possess 
were obtained by this method, and I do not hesitate to afiirm that 
I believe it to be a decided improvement upon the older method. 
Time and space preclude me from giving even a brief outline of this 
process, but I can assure my readers they will find an adjunct of 
extreme utility in a mixture of Miiller s fluid and carmine dye of 
the original strength given by Beale's formulae. By the time that 
