Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

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$(&) Serum-albumin (3-4 per cent.). Its solution begins to be turbid at 60° C, and coagulation occurs at 73° C, the fluid becoming slightly more alkahne at the same time. If sodium chloride be cautiotisly added to serum, the coagulating temperature may be lowered to 50° C. Its specific rotatory power is from - 62-6 to-64-5° (Starke). It is changed into syntonin or acid-albumin by the action of dilute HCl, and by dilute alkalies into alkali-albuminate. [Effects of Starvation.—Starvation diminishes the quantity of albumin, and increases the quantity of globulin. During the time a Rhine salmon is in fresh water, it eats nothing ; the muscles lose 30 per cent, of their weight, and the testes and ovaries increase at the expense of the muscles {Miesclier), and at the same time the globulins of the blood—closely related to the globulins of muscle—are increased in amount, the maximum of this increase corresponding to the maximum growth of the ovary {Bunge). The globulins are increased at the expense of the albumins.] i- , t -u • Serum-albumin is absent from the blood of starving snakes (the ahmentary canal being empty), and reappears after they are fed [Tiegel), so that in a digesting snake the blood contains both proteids. i . i 4. [Serum-Albumin v. Egg-Albumin.—Although serum-albumin is closely related_ to egg- albumin, they differ—(a) as regards their action upon polarised light ; (&) the precipitate pro- duced by adding HCl or HNO3 is readily soluble in 4 c.c. of the reagent m the case of serum- albumin, while the precipitate in egg-albumin is dissolved with very great difficulty ; c) egg- albumin, injected into the veins, is excreted in the urine as a foreign body, while serum-albumm is not; [d) serum-albumin is not coagulated by ether, while egg-albumm is, it the solution is not alkaline (§ 249). Serum-albumin has never been obtained free from salts, even when dialvsed for a very long time.] . -, , iv, • After all the serum-globulin in serum is precipitated by magnesium sulphate, serum-aibumin still remains in solution. If this solution be heated to 40 or 50° C. a copious precipitate of non-coacrulated serum-albumin is obtained, which is soluble in water. If the serum-albumm be filtered from the fluid, and if the clear fluid be heated to over 60° C, Fredericq found that it becomes turbid from the precipitation of other proteids ; the amount of these other bodies, however, is small. [Proteids of the Serum.—Halliburton has shown by the method of fractional heat-coagulation {i.e., ascertaining the temperature at which a proteid is coagulated, filtering the fluid and again heating the filtrate to a higher temperature), that from the same fluid perhaps two or more proteids, all with different tempera- tures of coagulation, may be obtained. Care must be taken to keep the reaction constant. He finds that serum-globulin coagulates at 75°C, while serum-albumm in reality consists of three proteids, which coagulate at different temperatures: (a) at 73°, {ß) at 77°, and (y) at 84° C] [Precipitation by Salts.—Sulphate of magnesia not only precipitates serum-globulin, but also fibrinof^en. The fluid must be shaken for several hours to get complete saturation Sodic sulphate, when added to serum deprived of its globulin by MgS04, precipitates serum-albumm, but it produces no precipitate with pure serum. In this way serum-albumm may be obtained in a pure, uncoagulated, and still soluble condition. Serum-globulin is thrown down by sodic nitrate, acetate, or carbonate ; Avhile all the proteids of the serum are precipitated by potassic acetate or phosphate, and the same result is brought about by adding two salts, g g., MgSO^ and ^ra.S04 (in this case sodio-magnesia sulphate is formed) ; MgS04 and KaN03 ; MgSO^ and KI ; I^aCl and NaoS04. After serum-globulin is thrown down by MgS04, the addition of MfrS04 and Na^SOj^or the double salt, precipitates the serum-albumm, which is still soluble 111 water. As sulphate of ammonia precipitates all the proteids except peptones, it may be used {Halliburton).^ j 0 \ i + [The plasma of Invertebrata (decapod crustaceans, some gasteropods, cephalopods, &c.) clots like vertebrate blood, and contains fibrinogen, but, in addition, there is found m it a substance corresponding to h£emoglobin, and called by Fredericq, haemocyanin. It exists like Hb 111 two conditions, one reduced and the other oxv-hfemocyanin, the former being colourless, the latter blue. In its general characters it resembles Hb, although it contains copper instead ot iron, and gives no absorption-bands {Hallihurton). In the blood of some decapod crustaceans there is a reddish pigment, tetronerythrin, which is identical with that m the exoskeleton and hypoderm. It belongs to the group of lipochromes, like some of the pigments of the retina. The htBmocyanin is respiratory in function, and it is remarkable that it is contained m the plasma, and not in the formed elements like the Hb of vertebrates. So that, stated broadly, in these invertebrates the plasma is both nutritive and respiratory m its functions, while in vertebrates the red corpuscles chiefly are respiratory and the plasma nutritive.]$