DIGITALIS GROUP. 
§§ 557-559*] 
45i 
of Bohm 1 and L. Brunton) 2 somewhat modifies Traube’s explanation, 
and the views generally accepted respecting the cause of the increased 
blood pressure may be stated thus :—The pressure is due to prolongation 
of the systolic stroke of the cardiac pump, and to the “ stop-cock ” action 
of the arteries ; in other words, there is an increase of force from behind 
(vis a tergo), and an increased resistance in front (vis a froute). 
§ 557. Action of the Digitalins on the Muco-Intestinal Tract and 
other Organs. —In addition to that on the heart, there are other actions 
of the digitalins ; for example, by whatever channel the poison is intro¬ 
duced, vomiting has been observed. Even in frogs this, in a rudimentary 
manner, occurs. The diuretic action which has been noticed in man 
is wanting in animals, nor has a diminution of urea been confirmed. 
Ackermann found the temperature during the period of increased 
blood pressure raised superficially, but lowered internally. According 
to Boeck, 3 there is no increase in the decomposition of the albuminoids. 
§ 558. The Action of Digitalin on the Common Blow-fly, —The senior author has 
studied the effects of digitalin, made up into a thin paste with water, and applied to 
the head of the common blow-fly. There are at once great signs of irritation, the 
sucker is extruded to its full length, and the fly works its fore feet, attempting to 
brush or remove the irritating agent. The next symptom is a difficulty in walking 
up a perpendicular glass surface. This difficulty increases, but it is distinctly observed 
that weakness and paralysis occur in the legs before they are seen in the wings. 
Within an hour the wings become paralysed also, and the fly, if jerked from its 
support, falls like a stone. The insect becomes dull and motionless, and ultimately 
dies in from ten to twenty-four hours. A dose, in itself insufficient to destroy life, 
does so on repetition at intervals of a couple of hours. The observation is not without 
interest, inasmuch as it shows that the digitalins are toxic substances to the muscular 
substance of even those life-forms which do not possess a heart. 
* 
§ 559. Action of the Digitalins on the Frog’s Heart.— The general 
action of the digitalins is best studied on the heart of the frog. Drs 
Fagge and Stevenson have shown 4 that, under the influence of digitalin, 
there is a peculiar form of irregularity in the beats of the heart of the 
frog ; the ventricle ultimately stops in the white contracted state, the 
voluntary power being retained for fifteen to twenty minutes after¬ 
wards ; in very large doses there is, however, at once paralysis. Lauder 
Brunton 5 considers the action on the heart to essentially consist in the 
prolongation of the systole. 
Atropine or curare has no influence on the heart thus poisoned. If 
the animal under the influence of digitalin be treated with muscarine, 
it stops in diastole instead of systole. On the other hand, the heart 
poisoned by muscarine is relieved by digitalin, and a similar influence 
appears to be exercised by atropine. The systolic stillness of the heart 
1 Archiv f. d. Ges. Phys., v. 153. 
2 On Digitalis, with some Observations on the Urine, Lond., 18G8. 
3 Intoxication, p. 404. 
4 Guy's Hosp. Reports, 3rd ser., xii. 37. 
5 On Digitalis, with some Observations on the Urine, Lond., 1868. 
