32 
pigs of 240 grams weight until the amount is found which will kill 
the animal in one and one-half to two hours. Their standard dose 
then, which they confirm by injecting like amounts into five or six 
animals, is that amount which would kill a guinea pig of 240 grams 
weight in one and one-half to two hours. They carried out a series 
of experiments to compare the digitoxin content of tinctures with 
the physiological activity. These results are tabulated on page 9. 
EXPERIMENTAL WORK. 
As will be seen from a study of the literature that has been given 
there are essentially three methods used for the biological assay of the 
members of the digitalis series, the others being merely modifications 
departing more or less widely from what we may consider the primary 
groups. These may be classified as follows : A toxic method, in which 
frogs, guinea pigs, or some of the higher animals are used; second, a 
method using the frog’s heart, which is perfused in some cases while in 
others it is simply exposed and systolic standstill is watched for (this 
in Focke’s method is reached in from seven to twenty minutes, while in 
others a longer interval of one or two hours is allowed) ; the third class 
includes those methods which aim at a comparison by means of the 
relative effects upon the blood pressures of some of the higher animals. 
One of the objects of the present study has been to examine into 
the results of these various methods to find if possible if one possessed 
a marked advantage over the others, and, most important of all, to 
see whether the different methods would give anything approaching 
uniform results in a comparative study of a number of digitalis prep- 
arations, some of which have been made according to the pharma- 
copoeial requirements, while others had been manufactured according 
to some special method devised by individual pharmaceutical houses. 
A study of these preparations constitutes an important part of the 
work, but was not the primary object of the research. 
With these objects in view we have examined nine preparations of 
digitalis, namely : Fluid extracts prepared according to the U. S. Phar- 
macopoeia, VIII, by Messrs. Parke, Davis & Co., Detroit; Sharpe & 
Dohme, Baltimore; Nelson, Baker & Co., Detroit; Hance Brothers 
& White, Philadelphia. In addition to these we examined several 
proprietary preparations as follows: Three specimens of Digitalone, 
prepared by Parke, Davis & Co.; a fat-free tincture of digitalis 
(Digitol), prepared by H. K. Mulford & Co., Philadelphia; Digitalis, 
Specific Medicine, manufactured by Lloyd Brothers, Cincinnati; a 
Concentrated Tincture of Digitalis (1 to 4), prepared by Burroughs, 
Wellcome & Co., London, and finally a purified “ Normal Tincture,” 
prepared by William S. Merrell & Co., Cincinnati. 
Digitalone is said to be a “ nonalcoholic permanent solution of 
digitalis” corresponding in strength to the U. S. Pharmacopoeia tinc- 
ture and physiologically standardized. The manufacturers state that 
