fITm^^^^^ Royal Microscopical Society, 99 
the border of cement having permitted the water to evaporate. 
Incomparably the best cement I nave met with is one which is much 
used in Germany, consisting of a solution of gum-mastic in chloro- 
form, thickened with nitrate of bismuth.* This may be easily kept 
at the proper degree of consistence by the addition of a few drops 
of chloroform from time to time. I use it also for the specimens 
mounted in glycerine and carbolic acid. It does not run in, it 
hardens quickly, and when thoroughly dry has a stone-like con- 
sistence and is not liable to crack. 
The Mounting of Sections of Brain and Spinal Cord, — There 
is now no longer any particular art or practice required to enable 
persons to mount and preserve successfully sections of brain and 
spinal cord. The best methods for ordinary use that I know are 
the two already described, as applicable for sections of other organs. 
These are suitable both for anatomical and for pathological investi- 
gations, and specimens so prepared, without tinting, preserve their 
characters with less change than when prepared by any other 
method that I have tried. It is, however, I think, more desirable 
to tint specimens of nerve-tissue that we may wish to preserve than 
when we are dealing with sections of other organs, since these derive 
a more than proportional advantage from the process.t 
The simple process with spirit-varnish is also applicable for the 
preservation of sections of nerve-tissue, but it is not nearly so 
useful as the others. When first mounted in this way, the sections 
have almost precisely the same appearance and transparency as 
they would have if immersed in glycerine ; but, very slowly, they 
become more transparent, and at last, after about six weeks, they 
get into a stationary condition, which accords, as nearly as possible, 
with the state of specimens mounted by either of the other two 
methods. Thin sections preserved in this way should always be 
tinted pretty deeply. 
The solution of glycerine and carbolic acid is also a medium 
which may be often used with great success for the preservation of 
very delicate sections of nerve-tissue. I have found this method of 
great assistance when investigating the anatomy of the brain and 
spinal cord, in some of the lower vertebrata. 
But I now come to the description of a method which is en- 
tirely new as regards the results which it is capable of producing — 
applicable for anatomical rather than pathological investigations — 
the bringing of which, to its present state, has cost me much time 
and labour. The method is only a modification of one of the 
* The solution of mastic in cliloroform should be nearly a saturated one, and a 
considerable quantity of bismuth must be added — the cement should be of a dead- 
white colour. It may be obtained from Mr. Ladd, of Beak Street. 
t I may state also that Mr. Matthews, of Portugal Street, has lately made for 
me a very excellent Valentin's knife, of a much larger size than those ordinarily 
employed, with which most excellent sections of hardened organs may be made. 
