— 14 — 
break up the material. Even tlie removal of the fluid by careful décantation or by means 
of a pipette is not unfrcquently disastrous, as the flow of liquid may suffice to dis- 
integrate the fragment, or the tissue may run up the pipette as a sticky, oily, brown 
fluid containing a few shreds. 
The difficulty is obviated by placing the piece which is to be softened on a small 
wire -pi at form, and adding softening fluid until the layer of reagent above and below the 
tissue are about equal. When the tissue is softened sufficiently, the lower tliird of the 
fluid, containing most of the colouring matter, is pipetted off and replaced by absolute 
alcohol. The same process is repeated on three consecutive days, and on the fifth day, 
the tissue has become so firm that all the fluid can be poured off and replaced by ab- 
solute alcohol or acetone. 
Under the influence of the solution, the mummified pieces become of a grey colour 
and somewhat transparent, as if they had been plunged for some hours in a clearing fluid 
e. g. turpentine or oil of cloves. A certain amount of differentiation is then noticeable : 
the mucous membrane of the intestine stands out from the muscular layer, the liver 
tissue from the Glisson's capsule, the pleura from tlie lung; but as alcohol is added, all 
differentiation disappears, and every tissue, though remaining pliable, becomes opaque 
again and of a dirty-grey colour. 
The material is now plunged in chloroform. Sometimes this liquid extracts a 
further quantity of colouring matter ; at other times a precipitate is formed. Imbedding 
in paraffine, carried out in the usual manner, then follows, and the pieces are ready for 
cutting. Very thin sections (1 division of Minot's microtome) are easily obtained, but 
present no advantages. The famous dictum attributed to Virchow « nur so dick wie 
môglich» is certainly true for this work. For staining, acid and basic dyes are equally 
useful. The best colorations are obtained with a dilute solution of Bohmer's haemat- 
oxylin or a 0,5 "/o solution of acid fuchsine. After staining, the sections are dehydrated, 
cleared and mounted in Canada balsam in the usual manner. 
HISTOLOGICAL EXAMINATION OF THE SKIN. 
Pre-historic I obtained from the Museum in Cairo particles of skin of the bodies of the Hearst 
bodies. collection, which, I am informed, are between 8000 and 12000 years old. The tissue was 
extremely fragile and disappeared almost entirely, in the ordinary softening solution. 
The skin could be prepared for section by using a solution containing only 0,25-0, 500/o 
of carbonate of soda. In such preparations the epidermis had completely disappeared 
but the dermis had retained its peculiar structure fairly well. The extraordinary part, 
however, is that many of the nuclei of the subcutaneous tissues still stained darkly 
with haematoxylin (Plate V, Fig. 6). The amount of material at my disposal was so small 
that I was not able to get many preparations. 
