27 
subsequent injections to diminish the amount until that dose was 
reached which would stop the heart in the required time. He points 
out that the biological standardization is not easy on account of the 
irregularity of the reaction of frogs. To avoid this as much as possi- 
ble there should be taken into consideration the effect of season, 
species, body weight, temperature, condition of health, and, finally, 
a factor which can not be reckoned upon, viz, individual idiosyn- 
crasy. The frogs employed by Santesson were captured in the 
autumn and kept in a cool place until they were used, in November 
and December. Males of about 50 grams weight were selected and 
kept in the examining room at least one hour before they were used. 
With these precautions Santesson showed that tinctures prepared 
from different varieties of strophanthus seeds varied in strength in 
the ratio of 1 to 4. 
A second method of comparison was to perfuse the frog’s heart, 
using William’s apparatus, comparing the effect of the different drugs 
upon the pulse frequency, circulation rapidity (number of drops per- 
fused per minute), and the pulse volume. 
The results obtained by the two methods furnish a very interest- 
ing comparison. 
1. 
2 . 
3 . 
4 . 
5 . 
6 . 
Preparation. 
Lethal dose 
for intact 
frog. 
Lethal dose, 
isolated 
heart. 
0.063 
0 . 047 
.10 
.123 
.22 
.25 
.10 
.046 
.064 
.027 
.051 
.0925 
Santesson calls attention to the fact that a certain parallelism 
exists in the results obtained by the two methods, but it is certainly 
very slight. He explains the lack of closer agreement as being due to 
the fact that the poison would not be so uniformly distributed in the 
fluids of the intact animal as in a fluid used to perfuse an isolated 
heart. 
Dixon,® in a paper on the biochemical standardization of drugs, 
considers the frog as the most suitable animal for digitalis standardi- 
zation. In employing them the time of year should be taken into 
consideration, as they are most active and vigorous in the summer and 
least active in the spring, but their sensitiveness to digitalis will not 
vary over 50 per cent during the year. Those selected should be 
males of about 25 grams weight and free from abnormal conditions. 
The tincture, diluted with an equal amount of water, is injected into 
the dorsal lymph sac and 6 minims of this diluted tincture should 
a Dixon, Pharm. J. and Tr., London, 1905, p. 155; Manual of Pharmacology, 
1906, p. 34. 
