30 
on the basis of 100 grams frog’s weight. He also compared their 
action upon cats and dogs, these reacting by vomiting. He suggested 
on account of the regularity of the appearance of this symptom, 
that it might be thought of as an index of the potency of the drug 
but because of the variability of the reaction of the vomiting center 
he “considered it better to determine the amount necessary to pro- 
duce svstolic standstill which is, of course, promptlv followed by 
death.” 
In his article “Ueber die physiologische TTertbesthnmung von 
Arzneimitteln ” Gottlieb®, after discussing the work of Frankel, Zei- 
genbein, and Btihrer upon physiological standardization, mentions 
the results of his investigation upon the uniformity of digitalis leaves 
used in the clinics around Heidelberg, showing that they varied as 
much as fourfold. He calls attention to the necessity of a govern- 
ment institution where such preparations can be examined, a fact to 
which attention has been called by several earlier writers. 
In order to obtain a convenient method of designating the strength 
of preparations he suggests the adoption of a standard “unit,” using 
the term in the same way as it is used in connection with sera work. 
For such a unit he has adopted the following: “The smallest amount 
of the solution which will call forth systolic standstill of the heart of a 
R. temporaria of 30 grams weight in thirty minutes exactly.” In an 
infusion freshly prepared from 1 gram of good digitalis leaf powder 
there must be 30 to 40 units; the strongest leaves may contain 120units. 
He further points out that such a comparison on the frog’s heart is 
only possible when made with similar active constituents, such as we 
have in the leaves, infusion, and tincture of digitalis, but could not 
hold good with dissimilar constituents as, for instance, a comparison 
of strophanthus with digitalis. A further fact which he calls atten- 
tion to is that, in the methods usually employed in which the heart is 
to be brought to a systolic standstill in a certain short time, a strong 
solution of a substance, absorbed with difficulty, would appear weaker 
than a weak solution of easily absorbable substances. 
Sowton b undertook to examine the activity of twenty-six speci- 
mens of the tincture of digitalis by means of perfusing the hearts of 
rabbits. He chose animals weighing 3 or 4 pounds each, and, using 
the coronary vessels, perfused the right ventricle with a solution of dig- 
italis of a strength of 1 to 200 made up in Locke’s or Ringer’s solution. 
From his results he grouped the preparations into two classes, “strong” 
and “weak,” but later found that such a classification was impossible, 
as five of his specimens upon which seventeen experiments had been 
carried out were placed some in one group and some in the other, and 
yet they were probably alike, having been made in exactly the same 
a Gottlieb, Mtinchen. med. Wchnschr., 1908, LV, 1265. 
&Sowton, Brit. M. J., London, 1908, Xo. 2458, 310. 
