53 
but not very probable, when it is remembered with what rapidity the 
action appears when digi toxin in solution is injected. 
The reason that the “ frog’s heart profusion” method does not 
agree with the other frog methods is possibly due partly to the more 
uniform character of the solution of the poison in which the heart is 
bathed and also to the resinous precipitate which forms and falls to 
the bottom of the perfusion vessel and which no doubt contains some 
of the active constituents. 
From this short critical review of the different methods for stand- 
ardization it can easily be seen why no two methods of assay could be 
expected to give exactly the same relative values to a series of digi- 
talis preparations, especially when they are made according to radi- 
cally different methods, such differences as exist, for instance, be- 
tween a “Fat free” tincture and a “Specific medicine.” The agree- 
ment is much closer when the preparations are made according to the 
same formula as we have in the case of the official fluid extracts. 
It would appear then most desirable if manufacturing houses could 
agree upon a certain method to be used which would insure the 
different preparations upon the market under the same name having 
the same potency. As to the choice of such a method difficulties 
would arise, but certainly none which would appear insurmountable. 
The method chosen should be as simple as possible, and above all an 
action upon the circulation should be taken as a standard of comparison 
rather than an action upon the nervous system. Judged by these rules, 
some of the methods now in use are not suitable for the purpose. 
First, we have the toxic action upon the higher animals, which 
should not be used for the reasons given earlier. The technical diffi- 
culties of the Focke method, together with the question of complete- 
ness of absorption, exclude it. The perfusion of the frog’s heart is 
also excluded for reasons mentioned and also because it requires more 
skill to carry it out, and even then the variations in results are very 
great. The blood-pressure method upon cats and dogs commends 
itself on account of the close relation it sustains to the use of the drug 
in clinical practice. The objections consist in the difficulty of pro- 
curing these animals at times and also the necessity of carrying out 
repeated experiments to confirm the results, which a study of our 
tables show will vary very greatly. A dose of a certain preparation 
which in one animal may cause a rise of perhaps 70 or 80 per cent in 
blood pressure may in others not raise it more than one-quarter as 
much, but probably repeated tests will give reliable results. 
The toxic dose can also be obtained at the same time by using arti- 
ficial respiration, but, as our tables show, there need be no agreement 
between the two, and it therefore seems superfluous. This leaves, 
then, the two frog methods — the “ twelve-hour” toxic method and the 
