8 
in alcohol and chloroform. In watery solutions of the drug it is 
probably made soluble by the presence of other constituents of the 
plant, most likely the saponin-like body, digit onin. The digit oxin 
is readily broken up into digitoxigenin and the sugar, digitoxose. 
Schmiedeberg obtained toxiresin as a decomposition product, a body 
which is related in action to the picrotoxin group. 
A second glucoside is digitalinum verum or digitalin, which is 
soluble in alcohol but insoluble in chloroform or water. This breaks 
up into an inactive body digit aligenin and two sugars. The digita- 
linum verum is found mainly in the seeds. 
Digitalein 0 resembles digitalin very closely, differing from it, how- 
ever, in being soluble in water. 
Digitophyllin, another glucoside, which has been isolated, resembles 
digitoxin. 
While digitoxin is the most important constituent of the prepara- 
tions of digitalis it does not necessarily follow that the activity of the 
drug runs parallel with the digitoxin content. At least this is true as 
far as we can judge by the method which is available for the isolation 
of this body, viz, the Keller method or the Keller method as modified 
by Fromme. Keller’s method 5 for the isolation of digitoxin con- 
sists in the extraction of a certain amount of carefully dried and 
powdered leaves with dilute alcohol. The percolate is evaporated to 
drive off the alcohol and the residue is taken up with water and lead 
acetate added. A voluminous precipitate results, but only the first 
portion of the filtrate obtained is saved to avoid the uncertainty of 
attempting to wash the precipitate free from digitoxin. Sodium 
sulphate is added to the filtrate to precipitate any excess of lead and 
after standing four to five hours the clear liquid is decanted, made 
alkaline with ammonia, and shaken out with chloroform. The chloro- 
formic solution is evaporated and a yellow resinous mass, the digi- 
toxin, is left behind. This may be purified by taking it up with a 
small amount of chloroform and reprecipitating with a mixture of 
sulphuric and petroleum ether. 
Several workers have tried to find a relationship between the 
digitoxin content and the activity of the preparations, as determined 
by biological methods, but the results, in almost every case, have 
proved a failure, as will be seen by a study of the following tables, 
which we have brought together for the sake of comparison. 
Ziegenbein c conducted such a series of comparative experiments, 
estimating the toxic dose upon frogs, employing leaves obtained 
from various localities. 
a According to Kiliani, Miinchen. med. Wchnschr., 1907, LIY, 886, the widely adver- 
tised proprietary preparation digalen consists of a solution of impure digitalein. 
& Keller, Ber. d. deutech. pharm. Geselssch., Berl., 1897, VII, 125. 
cZiegenbein, Arch. d. Pharm., 1902, CCXL, 454. 
