716 
EDWARD W. SHANN. 
the ox’dinary x’oora temperatux’e indicates that the fat is in a 
liquid condition, as opposed to a fluid ci’ystalline condition ; 
for the staining is consequent upon the solution of the dye 
in the fat, and the solubility is greater in liquid fats than in 
fluid ci’ystalline, while in ci’ystalline fats it cannot occur 
(until they are melted). The fat-globules are only slightly 
I’efractile. These obsei’vations suggest tliat the fat is allied 
to olein, but it is unlikely that the deposit is composed of any 
one pure compound. 
A further examination of the fat was made by staining 
with Kultschitzky’s haematoxylin after mordanting with 
bichromate of potash. The significance of this method in 
relation to fats has been explained in a paper by Lori’ain 
Smith and W. Mair as follows 
“ Weigert’s bichromate haematoxyliu method for the staining 
of myelin has become firmly established in histology. On 
studying the efi^ect of the bichromate mordant on fatty tissue 
we were convinced that the myelin method could be extended 
to apply to ordinax’y fats such as occur iu fatty liver and fatty 
myocardium. This proved to be the case, and we found that 
the points on which the method depends are the length of time 
during which the bichi’omating is canned on, the strength of the 
solution, and the temperatui'e at which the solution is applied. 
We early discovei’ed that positive results could be obtained 
with formalin sections of fatty liver and heart if these wei’e 
moi’danted in a bichi’omate solution kept saturated at 37° C. 
After a fortnight of this ti'eatment sections of fatty liver or 
heart yield extremely well defined and sharp blue staining of 
the fat-globules with Kultschitzky’s haematoxylin followed by 
differentiation in Weigert’s borax fen’icyanide solution. On 
investigating the chemistry of this reaction Dr. Thorpe found 
that the process is due in the fii’st place to the oxidising 
action of the bichromate. In the pi’ocess of oxidation of a 
molecule of fat the oxide of chromium (CrOg) forms with it a 
compound which is pi’actically insoluble in fat solvents. This 
“ Fats and Lipoids in Relation to Methods of Staining,” ‘ Skandi- 
navischen Archivfiir Physiologie,’ 1911, p. 251. 
