MACDONNELL ON ANIMAL DEXTRINE. 
543 
Of the Formation of the Amyloid Substance of Bernard in the 
Flacenta and other Structures. 
Next to the liver the placenta was the first organ in which animal 
dextrine was found to exist. Bernard discovered it in the placents of 
rabbits, guinea pigs, etc., the epithelial cells of which are filled with 
it at an early period of their development. As met with in the pla¬ 
centa it has the same characters identical as when found in the liver. 
Its presence in the placenta- cells may be readily demonstrated under 
the microscope by the aid of the acidulated tincture of iodine; it 
may however be obtained from the placenta by any of the methods 
already mentioned in sufficient quantity to be submitted to chemical 
examination, converted into sugar, fermented, &c. The cells con¬ 
taining it appear to be situated principally between the maternal and 
foetal portions of the placenta. The multiple placentulae (cotyle¬ 
dons) of the ruminants do not contain any amyloid substance, but 
Bernard observed that in this class of animals this substance is found 
in certain cells of the amnion, which in some ruminants are collected 
in masses on the foetal surface of this membrane. These little 
masses, which true to his glycogenic theory he names “ les plaques 
hepatiques de l’amnios,” in the cow are studded in great numbers 
over the inner surface of the amniotic membrane : to the naked eye 
they look like drops of bees’ wax of various sizes, from that of a 
millet seed to that of a split pea, or larger, sticking over the amnion 
but not evenly distributed over it. These amyloid patches of the 
amnion have not the appearance of being glandular bodies, but con¬ 
sist of large epithelial scales filled with amyloid substance. In the 
sheep, patches of the same kind as in the cow do not exist. In this 
animal the amyloid substance exists in the epithelial cells which line 
the sac of the amnion and in the papillae found in this membrane 
where it covers the funis and elsewhere. It is apparently about 
equally abundant in the placenta of cats and rabbits, and in such it 
is found in larger quantity at a time when the growth of the foetus 
is progressing rapidly. The placenta taken from a single female 
rabbit four weeks pregnant gave five grains, those from a female cat 
five weeks pregnant, six grains. Shortly before the birth of the 
young it has almost, if not totally, disappeared from the placenta. 
The presence, however, in the amnion or placenta of epithelial 
scales, containing amyloid substance, is a fact of quite secondary 
importance to the general fact that this substance enters largely into 
the constitution of most of the tissues of the embryo. Its existence 
does not indicate a new function of an organ or tissue doing tempo¬ 
rarily the duty of the liver, but it indicates a new fact with regard to 
the development of certain structures :—a new property of tissue. 
By observing that lactic acid was abundantly developed in the 
muscles of the foetus, Prof. Claude Bernard was led to discover 
sugar in this tissue, and subsequently amyloid substance. In his 
N. II. R.—1863. 2 O 
