Text-book of human physiology : including histology and microscopical anatomy with especial reference to the practice of medicine / by L. Landois.

  • Landois, L. (Leonard), 1837-1902.
Date:
[1904], ©1904
Catalogue details

Licence: Public Domain Mark

Credit: Text-book of human physiology : including histology and microscopical anatomy with especial reference to the practice of medicine / by L. Landois. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    45/1048 (page 29)
    PHYSIOLOGY OF THE BLOOD. PHYSICAL PROPERTIES OF THE BLOOD. The color of the blood varies from bright scarlet-red in the arteries to the deepest dark bluish-red in the veins. Oxygen, therefore also the air, makes it bright red, while deficiency in oxygen renders it dark. The oxygen-free venous blood is dichroic, that is, it appears dark red in reflected light and green in transmitted light. In thin layers the blood is opaque, as one can readily convince himself, if blood be poured upon a glass plate and be permitted to flow off, by attempting to read printed matter through it. The blood thus behaves as a covering pigment, as its coloring matter is suspended in the plasma in the form of small granules, namely, the red blood-corpuscles. For this reason the granular coloring matter of the blood can be separated from the blood-plasma by tiltration. This, however, is possible only after admix- ture of the blood with fluids that render the blood-corpuscles rough or viscid. If mammalian blood is mixed with one-seventh of its volume of concentrated sodium sulphate, or if frog's blood is mixed with two per cent, solution of cane sugar, and then filtered, the blood-corpuscles will remain upon the filter. The reaction of blood is alkaline from the presence of disodium phosphate (Na^HPO^). The alkalinity rapidly diminishes in intensity after escape from the vessel, and the more rapidly the greater the pre- vious alkalinity. The change depends upon the development of an acid, in which the red blood-corpuscles take part in consequence of a decomposition of as yet undetermined origin. This generation of acid is increased by high temperature and the addition of alkali. The alkalinity of the blood is diminished (A) by active muscular exercise, in consequence of the development of acid in the muscular tissue. (B) By coagulation. Fresh clot has a more intensely alkaline reaction than blood-serum. (C) After the persistent use of soda the alkalinity of the blood is increased, and after the use of acid it is diminished. (D) Old blood or blood dissolved with water from dry places generally has an acid reaction. The blood of children and women exhibits a lesser degree of alkalinity than that of men, and that of nursing women a lesser degree of alkalinity than that of pregnant women. The alkalinity is less also dur- ing digestion than during fasting. Method of Examination.—As in consequence of the normal color of the blood red litmus-paper cannot be employed directly in testing the reaction, the following plan is pursued: Blood is mixed with an equal volume of concentrated solution of sodium sulphate, and the mixture is placed upon highly porous and sensitive lilac- tinted litmus blotting-paper. The blood-corpuscles remain upon the surface while fluid is taken up by the paper and gives rise to the reaction. For the quantitative estimation of the alkalinity dilute tartaric acid is added to a volume of blood (7.5 grams of crystalline tartaric acid to i liter of water, 1 cu. cm. of which saturates 3.1 mg. of soda) until the blue paper is reddened. One hundred cu. cm. of human blood contains the alkaline equivalent of from 260 to 300 mg. of soda (in guinea-pigs 150 mg., in camivora 180 mg. of soda). Landois' method for the quantitative determination of the alkalinity of the blood with only a few drops of blood: Tartaric acid in the concentration already stated is emploj-ed to neutralize the alkalinity of the blood. Of this the following mix- tures are made by addition of concentrated solution of neutral sodium sulphate: (i) 10 parts of tartaric-acid solution and 100 parts of concentrated sodium-