[580] The following is a brief summary of observations on the blood pressure; four stages may be noticed—(1) Rise of normal blood pressure, not necessarily accompanied with a diminution of pulse frequency; (2) continuation of heightened blood pressure, the pulse being raised beyond the normal rate; (3) continued high pressure, with great irregularity of the heart and intermittent pulse; (4) quick depression of pressure, sudden stopping of the heart, and death.
[581] According to Boehm (Arch. f. d. Ges. Physiol., Bd. v. S. 189) and to Williams (Arch. f. exper. Pathol., Bd. xiii. S. 2), the rise of pressure is due entirely to the heart, and not to the contractions of the small arteries; but I fail to see how the small arteries can contract, and yet not heighten the pressure.
§ 546. Post-mortem Appearances.—In the case of the recruit poisoned by digitalis leaf ([p. 425]), the blood was found dark and fluid; the right ventricle and auricle of the heart were filled with blood, the left empty; the brain and its membranes were anæmic; the stomach and mucous membrane of the intestines were in parts ecchymosed, and there were patches of injection. In the case of the widow De Pauw, poisoned with digitalin by the homœopath (Conty de la Pommerais), the only abnormality discovered was a few hyperæmic points in the mucous membrane of the stomach and small intestines. It is then certain that although more or less redness of the lining membrane of the intestine track may be present, yet, on the other hand, the active principle of the digitalis may destroy life, and leave no appreciable sign.
§ 547. Separation of the Digitalins from Animal Tissues, &c.—It is best to make an alcoholic extract after the method of Stas, the alcohol being feebly acidulated by acetic acid, and all operations being carried on at a temperature below 60°. The alcoholic extract is dissolved in water feebly acidulated by acetic acid, and shaken up, first with petroleum ether to remove impurities (the ether will not dissolve any of the digitalins), then with benzene, and, lastly, with chloroform. The benzene dissolves digitalein, and the chloroform, digitalin and digitoxin. On allowing these solvents to evaporate spontaneously, residues are obtained which will give the reactions already detailed. Neither the bromine nor any other chemical test is sufficient to identify the digitalins; it is absolutely necessary to have resource to physiological experiment. The method used by Tardieu in the classical Pommerais case may serve as a model, more especially the experiments on frogs. Three frogs were properly secured, the hearts exposed, and the beats counted. The number of beats was found to be fairly equal. Frog No. 1 was placed under such conditions that the heart was constantly moist. Frog No. 2 was poisoned by injecting into the pleura 6 drops of a solution in which 10 mgrms. of digitalin were dissolved in 5 c.c. of water. The third frog was poisoned by a solution of the suspected extract. The number of beats per minute were now counted at definite intervals of time as follows:—
TABLE SHOWING THE ACTION OF DIGITALIN ON THE FROG’S HEART.
| Frog No. 1. Unpoisoned. | Frog No. 2. Poisoned by a known quantity of digitalin. | Frog No. 3. Poisoned by the suspected extract. | |||||
|---|---|---|---|---|---|---|---|
| No. of beats per minute. | No. of beats per minute. | No. of beats per minute. | |||||
| After | 6 | minutes, | 42 | 20 | 26 | ||
| „ | 10 | „ | 40 | 16 | irregular. | 24 | irregular. |
| „ | 20 | „ | 40 | 15 | 20 | irre„ | |
| „ | 28 | „ | 38 | 0 | 12 | very irregular. | |
| „ | 31 | „ | 36 | 0 | 0 | ||
In operating in this way—which is strictly comparative, and, with care, has few sources of error—if the heart of the frog poisoned with the unknown extract behaves in the number and irregularity of its contractions similarly to that of the digitalin-poisoned heart, it is a fair inference that, at all events, a “heart-poison” has been separated; but it is, of course, open to question whether this is a digitalin or one of the numerous groups of glucosides acting in the same way. If sufficient quantity has been separated, chemical reactions, especially the bromine test (Grandeau’s test), may decide, but with the larger number (yearly increasing) of substances acting similarly on the heart, great caution in giving an opinion will be necessary.