28 
produce systolic stoppage of the heart in one hour. Dixon proposes 
this as a standard “unit,” and if a certain tincture does not corre- 
spond to this strength the pharmacist should make the necessary 
calculations, so as to give the patient a uniform product. The writer 
thinks the method proposed above may be accurately controlled by 
experiments upon rabbits. 
In his Manual of Pharmacology (1906, p. 34), after discussing the 
frog method, Dixon says: “These drugs can be standardized more 
accurately by perfusing the isolated rabbit’s heart with Ringer’s 
solution and subsequently adding the drug.” However, Sowton’s 
results, referred to later, hardly confirm this statement. 
Haynes ® sought to determine the relative activity upon the heart 
of the three important members of the digitalis group — digitalis, 
strophanthus, and squills — using tinctures which he prepared very 
carefully according to the British Pharmacopoeia. He standardized 
these by determining the smallest dose of each which, when injected 
into the dorsal lymph sac of a frog, would cause systolic stoppage of 
the heart. He also carried out comparative tests upon rabbits with 
these preparations, injecting the drugs invariably into the stomach 
and watching for changes in the blood pressure as well as for the toxic 
effects upon the heart. In addition he studied their relative strength 
upon the excised hearts of rabbits, employing a modification of the 
Langendorff method and compared especially the effect upon the rate 
and the quality of the heart beat. 
In respect to the suggestion that, on account of the variation in the 
strengths of galenical preparations of this series, the active principles 
should be substituted for them in general practice, Playnes says that 
in their isolation much of their potency is lost and that they require 
standardization even more than the galenicals. 
The Pharmacopoeia of Norway (1870) directed that official prepara- 
tions of digitalis should be made from the plant growing wild in 
Norway. Wang 6 undertook to determine whether the plants grow- 
ing in that country offered any advantage as regards strength over 
those growing elsewhere. 
He used frogs (Rana temporaria) and adopted Focke’s method of 
assay described earlier. His experiments were carried out in Strass- 
burg in October, 1905. The frogs were kept in a cool cellar, and the 
evening before they were needed they were placed in a cool room, 
being brought to ordinary room temperature two or three hours before 
they were used. The animals were injected with the 10 per cent 
infusion through the lateral lymph sacs into the two thigh lymph 
sacs. In this manner any escape of the drug was avoided when the 
chest was open. The heart was exposed as soon as the animal was 
a Haynes, Bio-Chem. Jour., 1906, I, 63. 
b Wang, Festschr. f. Olof Hammarsten, 1906. 
