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In order to obtain the precipitate, acid, sodium chloride, and hydrogen peroxide must all be present, but acetic, phosphoric, or sulphuric acids may be substituted for lactic acid.

Lactic acid and sodium chloride are both present in sweat, and hydrogen peroxide can also be shown to be present by the tetramethylparaphenylenediamine paper test; as it is also in certain tissues; the question arises whether the deep cutaneous tissues are able by this means to cause coagulation of proteïds circulating in the lymph; this and the questions whether the coagulation of blood and of muscle plasma and the formation of casein in milk may be similarly explained, are not yet considered proven. W. D. H.

Deterioration of Diastase by the Action of Heat. By E. BOURQUELOT (Compt. rend., 104, 576—579).—A solution of diastase is heated at 68° for several hours, and is then allowed to act on potato starch. The enfeebled diastase, even when employed in large excess, has lost the power of carrying the hydration of the starch to its utmost limit, but accomplishes the first stages of the alteration with practically the same rapidity as natural diastase. It would seem that it is not the quantity of the ferment which is diminished, but its quality which is altered. It may, however, be supposed that natural diastase is a mixture of two or more soluble ferments, which are successively destroyed by the action of heat. C. H. B.

Physiological Chemistry.

Specific Gravity of Human Blood. By E. L. JONES (J. Physiol., 7, 1-14). The observations were made by Roy's method (Proc. Physiol. Soc., 1884). A drop of blood is introduced into a mixture of glycerol and water of known specific gravity; if the drop tends to rise or sink it is assumed that it is of lower or higher specific gravity respectively than the liquid in which it is placed. By having ready to hand a number of solutions of glycerol and water of different specific gravities, it was not difficult to find one in which the drop of blood neither rose nor sank, and as its specific gravity was known, the specific gravity of the blood examined was thus found. Fermentation changes are prevented in the standard solutions by adding to them either thymol or mercuric chloride.

The principal results obtained were as follows:—

1. The specific gravity is highest at birth, at a minimum between the second week and the second year, and rises gradually to a point attained in the male between the ages of 35 and 45, in the female after the climacteric.

2. The specific gravity of the blood tends to be higher in the male than in the female; and in the latter preguancy diminishes it to a slight extent.

3. The immediate effect of mixed food is to cause a fall in specific gravity; but if alcohol is taken this effect is not observed.

4. Exercise if gentle causes a fall; if violent leading to perspiration, it causes a rise in specific gravity.

5. The specific gravity of the blood in a passively congested part of the body is higher than elsewhere.

6. Diurnal variation. The specific gravity of the blood tends to fall during the day and to rise during the night.

W. D. H.

Causes of the Alteration of Blood in Contact with Air, Oxygen, and Carbonic Anhydride. By A. BÉCHAMP (Compt. rend., 104, 587-589).-Separate quantities of blood were treated with (1) a current of ordinary air, (2) a current of air washed with water, (3) a current of pure, washed oxygen, and (4) the air was expelled by means of carbonic anhydride, and the vessel closed.

In no case, even after a month, did the blood acquire a disagreeable odour, although, as in the first experiment, it contained a large number of bacteria. Between 20° and 25° the blood in contact with air remains red, and deposits no crystals; that in contact with oxygen at 24-26° deposits some crystals after the second day, and their number slowly increases. The blood in contact with carbonic anhydride deposits no crystals at 20-28°, and the blood becomes dark-red; at 33–40° crystals appear, and the blood becomes brown. Addition of one-fourth the volume of a 0.2 per cent. solution of phenol accelerates the formation of these crystals. The destruction of the corpuscles is evidently not due to the action of oxygen, since it takes place most readily in presence of carbonic anhydride. The formation of the crystals and destruction of the corpuscles in presence of carbonic anhydride is a function of the temperature, and this is probably true also in presence of air or oxygen.

Other experiments show that none of the substances separated from blood, such as hæmoglobin and albumin, alter under the conditions described, and the changes observed in blood by Pasteur and by the author can only be due to the activity and influence of the microzymes in the blood. C. H. B.

A First Product of Gastric Digestion. By K. HASEBRoek (Zeit. physiol. Chem., 11, 348-360).—When fresh fibrin is employed in experiments on artificial gastric digestion, it is found that previous to the formation of parapeptone or syntonin, and propeptone and peptones, there is a substance present which is a globulin. It is soluble in weak saline solutions, precipitable on dilution with water, by saturation with sodium chloride or magnesium sulphate, and can be separated by fractional heat coagulation into two proteïds which coagulate respectively at the temperatures 55° and 72°. Supposing fibrin to be formed from fibrinogen and serum globulin (Schmidt), the conclusion is drawn that the first effect of gastric juice or fibrin is to separate it into two substances, one of which corresponds exactly with one of the components of fibrin (serum globulin), and the other only differs from the other component of fibrin (fibrinogen) in

having lost the power of coagulating under the influence of the fibrin ferment.

If boiled fibrin be employed, no such globulins are formed in gastric digestion.

One experiment only was made with fibrin that had been kept under alcohol; from it a small amount of globulins was obtained by the action of artificial gastric juice; as, however, the fibrin had only been under alcohol for two days, it is probable that some uncoagulated fibrin was still present. Experiments with egg albumin coagulated either by heat or by alcohol, showed that no globulin was yielded by gastric digestion. Lastly, it was found by using a pure solution of trypsin, or at least one which contained no globulins, and subjecting fibrin freed from adherent globulins by washing it with a solution of ammonium chloride, to its action in an alkaline medium, that the first effect of tryptic digestion was exactly the same as that of gastric digestion. W. D. H.

Intestinal Digestion in the Horse. By H. GOLDSCHMIDT (Zeit. physiol. Chem., 11, 286-305).-The reaction of the contents of the small intestine of the horse was usually as follows:-At the duodenal end the reaction was acid; then after the first 15 to 20 inches neutral or weakly alkaline; in the remainder of the small intestine it was alkaline, and towards the end of the ileum strongly alkaline. The consistency was slimy, especially in the duodenum, the sliminess seeming to depend on the presence of starch; the colour depends on the food, but the colour of the intestinal juice is dark yellow, becoming darker brown down the intestine. The contents give the reactions of proteïds, peptones, and sugar, especially the latter; the amount present being on the average 0.5 to 1.5 per cent.

The digestion in the small intestine is in the horse not so important as in the stomach. Whilst in the stomach about 55 per cent. of the albuminous and about 40 per cent. of the non-nitrogenous constituents are digested, about 20 and 25 per cent. respectively represent digestion in the small intestine. During inanition an extraordinarily large quantity of fluid (4 to 6 litres) is present in the small intestine. With regard to the movement of the food, it was found that the first portions reached the colon about 8 to 12 hours after it was eaten. Digestion in the large intestine of the horse is not described.

W. D. H. Oxidation in the Animal Body. By C. WURSTER (Ber., 20, 256-263). Certain amines being well adapted to the study of oxidation processes, the following experiments were performed :

Tetramethylparaphenylenediamine was injected subcutaneously and into the veins of certain warm-blooded animals (rabbits, guinea-pigs, and pigeons), and soon caused the death of the animal after violent convulsions. Post-mortem examination gave in most cases a negative result; the base could not be discovered in the skin or muscles, as it had been oxidised to form a colourless substance. The liver and bile contained traces. Freshly captured frogs also oxidise the base quickly if its hydrochloride is employed. By using the acetate or sulphate subcutaneously, the muscles under the skin are seen during life to be

blue-violet. This colour is formed more quickly in the presence of air. The skin also contains the pigment, but appears to oxidise the colouring matter more slowly. After frogs have been kept a long time without food, their tissues burn the tetramethylparaphenylenediamine with greater difficulty, but better if muscular movements are brought about, and if a weak solution of sugar be added to the hydrochloride of the base. After intravenous injection of such a mixture into a frog, the unchanged substance is found after death in the liver, blood, bile, certain muscles, and the central nervous system, and the free base can be obtained by treating with sodium hydroxide and subsequent shaking with ether; treatment of the tissues with a solution of copper sulphate or of iodine gives a blue-violet coloration.

The liver in the air became deep-blue violet; certain muscles, especially of the trunk, also became violet, and darkened on exposure in the air; the muscles of the lower extremity which continued to move longest were free from colour, which they had probably oxidised. In the alimentary canal, the mucous membrane was colourless, marking it off sharply from the muscular coat, which became violet in the air. These facts show that protoplasm, although itself reducing, can on access of air bring about powerful oxidation, and that even after the death of the animal, further oxidation processes will go on in the cells which still retain vital power. Moreover, the organs which during life form glycogen, namely, the liver and resting muscles, produce oxidation only to a certain extent, whilst the acting muscles, the glands of the alimentary tract, and the skin, cause still further oxidation, resulting in the formation of a colourless compound from the amine. Dimethylparaphenylenediamine behaves similarly to the tetra-compound, but as its oxidation occurs more slowly, the effects on warmblooded animals can be observed better. 20 to 40 c.c. of a to 3 per cent. solution of the hydrochloride causes in warm-blooded animals violent convulsions and death, the symptoms much resembling those described by Brieger as the result of poisoning by tetanine. Weaker solutions do not kill so quickly; the muscles in certain cases became violet during life; and in these the base is no longer present as such; but as a rule in the muscles in the neighbourhood of the injection, and in certain cases in the tears and peritoneal fluid the base could be detected after treatment with sodium hydroxide and ether, or by the red colour produced by chromic and glacial acetic acids. In the lung, the blue oxidation product caused mottling, and both this organ and the muscle darkened as in the case of the tetra-compound on exposure to air. The blood contains the unaltered amine. Experiments on frogs gave confirmatory results. Muscle which had undergone heat rigor no longer produced oxidation changes; this is analogous to fibrin, which, as Scherer (Annalen, 40, 15) showed, does not decompose hydrogen peroxide after it had been boiled. The general conclusions drawn are: (1) That during life oxidation processes go on in the body, corresponding with the effect produced by ordinary oxidising agents on di- and tetra-methylparaphenylenediamine, which, causing them to take up 1 atom of oxygen, produces a blue-violet colour; or they may undergo still further oxidation, 6 atoms of oxygen being used to form carbonic anhydride from two methyl-groups, and

so convert the amine into a colourless derivative; (2) the oxidation of the amines occurs not in the blood, but in the tissues; (3) the secretions of the body are also strongly oxidising, in virtue of the hydrogen peroxide they contain; (4) the rapidity with which dimethylparaphenylenediamine is burnt in the tissues, as compared with what occurs in laboratory experiments or in the secretions, points to oxidation in the tissues as being brought about by atomic oxygen, which is probably produced, as Hoppe-Seyer suggests, by the action of nascent hydrogen (Abstr., 1886, 120).

Many of the foregoing experiments and conclusions run counter to those of Ehrlich (Das Sauerstoffbedürfniss des Organismus, Berlin, 1885). Ehrlich's methods are criticised by the author. W. D. H.

The Fate of certain Chlorine Compounds in the Organism. By A. KAST (Zeit. physiol. Chem., 11, 277-285).-Certain results of Mylius, showing the influence of the administration of chloroform on the amount of chlorine in the urine of the dog, which have not been hitherto published, are first given. The following example will illustrate the result arrived at:

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On the second day, 10 grams of chloroform were given; the next day's urine shows a great increase of sodium chloride. Ether given in similar amount produced no such change.

This research was now pursued further; the effect of the inhalation of chloroform was first tried on a dog. The following table shows the results obtained :

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The effect in the increase of chlorides is thus seen to be very marked after chloroform narcosis; whilst ether produces no effect. During the progress of the experiment, the animal was kept on a

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