Observations on the functions of the liver : more especially with reference to the formation of the material known as amyloid substance, or animal dextrine, and the ultimate destination of this substance in the animal economy / by Robert M'Donnell.

  • Robert McDonnell
Date:
1865
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the functions of the liver : more especially with reference to the formation of the material known as amyloid substance, or animal dextrine, and the ultimate destination of this substance in the animal economy / by Robert M'Donnell. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    birth, when, even after prolonged boiling, no trace of amyloid substance can be extracted from it. In the tissue of the lung of mammalian embryos, the amyloid substance is at one period present in immense quantity. After the watery part is driven off by evaporation, more than 50 per cent, of the dry residue is found to be nothing else than animal dextrine. As the organ approaches maturity, and the animal is about being born, but before it has yet drawn a single breath, the amyloid substance is found to be reduced to a very small quantity indeed, and in some instances to have absolutely disappeared. The following table shows the progress of this change in the lung of the embryo of the sheep, and, I believe, very closely represents the corresponding amount of change which takes place in the lung tissue of other embryos which I have examined, viz., of the rabbit, cat, dog, cow, rat, guinea pig:— Size and Condition of the Embryo. Amount of amyloid substance con- tained in 20 grains of the perfectly fresh lung tissue. 1st—Not quite 6 inches long, without any vestige of hair, 2nd—7 inches long, a trace of hair on the lip, 3rd—10 inches long, delicate hairs about the head, 4th—15 inches long, covered with delicate hairs, 5th—164 inches long, we^ covered with fine hair, 6th—Nearly 20 inches long, quite thickly covered with wool, and evidently very near the time of birth, 19 gr. 2 55 grs. 2 3 grs. 3 45 grs. 2-2 grs. A quantity too small to be estimated. It would be no easy matter to attempt to indicate precisely the condition of development of the embryo, at which the maximum amount of amyloid substance is to be found hi the tissue of voluntary muscle; in embryos of apparently the same age and condition of development, it is found to vary a good deal in amount. But this much may be asserted positively, that, for some time before birth, it has much diminished in quantity in this tissue, although generally existing in it in no- table amount up to and after birth.
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