16 
No reference is directly made in Jacquet’s paper as to the effect 
of the weight of the frogs upon the results, except, in the protocols, 
the size is noted as “ large’ 7 or “medium.” 
In his experiments upon rabbits he used two methods. Upon 
most he measured the effect upon the blood pressure and heart rate 
when the drug was injected into the jugular vein and calculated also 
the toxic dose per kilogram body weight. In other cases he injected 
the drug subcutaneously. 
It appears strange that, although so much work had been done on 
the comparison of the relative strengths of the different members of 
the digitalis group, no practical application was made of the methods 
developed until more than thirty years after Fagge and Stevenson 
published their results. As pointed out, it was not until 1898 that 
the application of these physiological tests was advised for the pro- 
duction of uniform pharmaceutical preparations. In that year 
Houghton a published his method for the physiological assay of 
strophanthus, basing it upon the fact that the killing power of the 
cardiac drugs for frogs of definite size and species, kept under proper 
conditions, is constant per gram of body weight. He had tried rab- 
bits, guinea pigs, and rats, as well as frogs, but came back to the 
latter as being most satisfactory as he found too great variation in the 
blood pressure of dogs and rabbits under the action of digitalis to 
allow of this method being of use. Any species of frogs may be 
employed, provided both the standard solution and the unknown 
preparation are tested upon the same species, for, while animals of 
different species vary in their reaction, those belonging to the same 
are much alike. Also frogs of any weight may be used, providing 
the proper allowance is made for the variation, but in testing a prep- 
aration, it is best to use frogs of nearly uniform size, varying from 
one another not more than 3 grams. The frogs to be employed 
should be freshly caught and carefully handled, being kept in wet 
moss until they can be placed in suitable pools at the laboratory. 
The dose of the drug to be tested is calculated according to the 
weights of the frogs to be employed and made up with salt solution 
so that it will measure about one-half cubic centimeter, and is then 
introduced into the abdominal lymph sac by means of a pipette. 
The frogs are placed in separate jars and allowed to remain for twelve 
hours, at the expiration of which time they are examined and note 
made as to the dead and living animals. By a preliminary' test in 
which the limits of dosage are quite wide some idea is formed as to 
the strength of the preparation and a second series of frogs is injected, 
still further narrowing the dose. When by this second group the 
probable toxic dose is obtained, a new series of five frogs is injected, 
and if the dose is correct at least three frogs out of the five should be 
“ Houghton, J. Am. M. Ass., Chicago, 1898, XXXI, 959. 
