Characters. - Light brown tasteless crystalline powder, with a faint smell somewhat like thymol.

Solubility. - Insoluble in water, soluble in 3 parts of alcohol, readily soluble in ether and chloroform, sparingly soluble in oils by means of warmth. Glycerine may be added to the alcoholic solution without causing a precipitate.

Pyrrol.

Pyrrol

Iodol.

Iodol

Action. - Like iodoform (p. 805). It may be given internally, in doses of 3 grains daily, without causing any irritation of the intestinal canal.

Use. - It is useful as a dressing in venereal sores, adenitis and periadenitis. It may be applied as a powder, sprinkled over the surface of the sore, or suspended in glycerine, dissolved in spirit, or as an ointment.

Strophanthus hispidus. [Kombe, Inee.] Not officinal. A plant belonging to the natural order Apocynacete, and the seeds of which are used in Africa as an arrow-poison.

Description. - The ripe follicles are 9 to 12 inches long and enclose 100 to 200 seeds, which contain the greatest proportion of the active principle. The seeds are oval, and are readily recognised by their comose appendages.

Composition. - The active principle is strophanthin, of which the seeds contain from 8 to 10 per cent. It is a crystalline glucoside, with a strongly bitter taste and a slightly acid reaction; readily soluble in water and rectified spirit, practically insoluble in ether, chloroform, benzene, and petroleum spirit. It yields, on heating with sulphuric acid, glucose and an insoluble body, strophanthidin.

Preparations.

Dose.

Tinctura Strophanthi (1 in 201)....................

5-10 min. or 1/2 to 2 min. frequently repeated.

Strophanthin ...............................................

1/120-1/60 gr. hypodermically.

1 A stronger tincture, 1 in 8, corresponding to the tincture of digitalis, has been chiefly used hitherto; but a tincture 1 in 20 is recommended by Fraser, and a formula for preparing it is given by him in the British Medical Journal, Jan. 22, 1887, p. 151.

Action and Uses. - Strophanthin, according to Fraser, is a muscle-poison, increasing primarily the contractile power of all striated muscles; the contraction becoming more complete and prolonged. It is a cardiac tonic (p. 331), increasing the length of the systole, and slowing the rhythm, acting like digitalis and producing a similar standstill in systole. Its action on the heart is much more powerful than that of digitalis. Strophanthus causes a rise of blood-pressure, due chiefly to the heart, since it does not produce so marked a contraction of arterioles as digitalis. In the normal animal it is sometimes diuretic (p. 432) and antipyretic. Strophanthus has been used as a tincture in cases of cardiac disease similar to those in which digitalis is serviceable. It is most beneficial in cases of mitral disease with great anasarca, in which it reduces the frequency of the pulse and makes it regular, while producing great diuresis. Strophanthin, hypodermically, acts in a similar manner. Strophanthus is said not to cause great sickness or gastro-intestinal irritation, and to have no cumulative effect. The exact utility of the drug has, however, not yet been determined, as it has not been sufficiently tried in cases of heart-disease.

Dead Space. - This name has been given by 0. Liebreich to the part of a fluid in which no reaction occurs between substances dissolved in it. Chloral hydrate and sodium carbonate in solution decompose each other, chloroform and sodium formate being produced, but this reaction does not occur equally throughout the whole solution. If the solution be mixed in a test-tube the fluid will be seen to become milky, from the formation of minute globules of chloroform; but just below the surface of the fluid this reaction does not occur, and a clear space is observed, a section of which has a bi-concave formation, as it is bounded above by the concave level of the fluid and below by the convex surface of that part of the liquid in which no action occurs.

Iodol Tetraiodpyrrol C4I4NH Not officinal 335

Fig. 228. - Diagram showing the dead space and space of reaction in a mixture of solutions of chloral hydrate and sodium carbonate.

If the mixture is placed in horizontal capillary tubes, the dead space in which no reaction occurs is at each end of the liquid; if the entire length of the column of liquid in the tube is shorter than the combined length of the two dead spaces no reaction occurs at all. This absence of reaction renders it probable that the chemical processes which occur in the confined space of a living cell may be very different from those in an ordinary test-tube, on account of the difference in physical conditions as well as from the complex phenomena which we are accustomed to class as vital. The same absence of reaction in certain parts of a liquid can be observed with other mixtures, and a convenient one for demonstration is a mixture of iodic acid, sulphurous acid, and starch. When these substances are mixed, iodine is set free, and an intense blue colour produced. If they are mixed in a large beaker the reaction occurs more quickly than if they are contained in a narrow glass tube. In a tube also it can be seen that the reaction begins in the centre, so that occasionally one may notice a blue thread occupying the centre of the liquid, while that part of it which lies adjacent to the walls of the tube is still colourless. When a series of vesicles made of membranes such as calves' peritoneum are filled with the mixture just mentioned, it can be seen that the reaction occurs quicker in the larger spheres, and that it generally begins in the centre of the fluid. When one vesicle is contracted in the centre by a ligature, so as to form two smaller vesicles connected with each other, two centres of reaction may be frequently observed instead of one. Although this discovery has not yet been fully worked out, it promises to have a most important bearing on our ideas regarding the action of drugs in living tissues.

Fig. 229.   Diagram showing the two dead spaces in a capillary tube.

Fig. 229. - Diagram showing the two dead spaces in a capillary tube.

Iodol Tetraiodpyrrol C4I4NH Not officinal 337

Fig. 230. - Diagram showing the absence of reaction in a capillary tube where the column of liquid is shorter than the length of the two dead spaces in a tube of that size.