272 
These questions are among the most interesting and delicate of phy- 
siology, and certainly do not bear to be treated of dogmatically. 
In the following communication the term ‘‘amyloid substance” shall, 
forreasons elsewhere indicated, besubstituted for “‘ glucogenic substance;”’ 
and it may be well to state that this is a generic term applied to animal 
substances having special characters, apparently forming a link between 
the immediate (azotized) principles of animal structures, and the (non- 
azotized) vegetable formations, in some varieties presenting the charac- 
teristics of starch or dextrine of vegetable origin, yet in others giving 
unquestionable indications of the presence of nitrogen. 
The species of amyloid substance spoken of in this memoir belongs 
to the former group, and, being free from the intimate admixture of azo- 
tized matters, is consequently distinct from the amyloid substance of 
Virchow, which, although in histological characters analogous to cellu- 
lose and starch, yet, as met with in the prostate gland, the spleen, cho- 
roid plexus, &c., has not yet been shown to be convertible into sugar 
capable of fermentation. 
The first may be indicated as the amyloid substance of Bernard, or 
(being evidently nearer to the vegetable kingdom), of first species ; the 
latter as amyloid substance of Virchow, or of the second species. 
The amyloid substance of Bernard, or of the first species, is a ter- 
nary compound isomeric with dried grape sugar. It is a neutral, whitish, 
inodorous, insipid matter, soluble in water, insoluble in alcohol and 
strong acetic acid. 
In the presence of saliva and other animal ferments it is converted 
into sugar, which ferments on the addition of yeast, and reduces the 
cupro-potassic solution ; iodine in contact with it produces a peculiar 
brown coloration, more or less intense, disappearing on the application 
of heat, and reappearing when the fluid cools below 80°; like dextrine, 
it causes the plane of polarization to deviate to the right. 
It was first obtained by Bernard by treating the boilings of the liver 
with four or five times its volume of absolute alcohol, and subsequently 
freeing the precipitate thus formed from azotized matters by boiling it 
for some time in a concentrated solution of caustic potash. This method 
is objectionable. The acetic acid process, although not economical, is 
preferable, and, indeed, is invaluable as a test for the presence of the 
substance in question in the various tissues of the organism. 
The organ or tissue to be examined is boiled in a small quantity of 
distilled water; the whole is then bruised in a mortar with animal 
charcoal, thrown on a filter, and some drops allowed to fall into glacial 
acetic acid. If amyloid substance of the first species is present, it forms 
a more or less abundant white, flaky precipitate. 
Gelatine and casein are not arrested upon the filter by the animal 
charcoal, but the first is soluble in acetic acid, and the latter, although 
at first precipitated, is at once re-dissolved by the glacial acid. These 
substances, therefore, do not interfere where acetic acid is used, but the 
contrary is the case with alcohol. 
If the tissue, while stillraw, be pounded in a mortar with animal 
