43 
end reaction is the stoppage of the frog’s heart in systole, the chief 
differences between the various methods being dependant upon 
variations in the time factor. 
The one-hour method.— In this method the frogs are secured and 
kept in the manner already described, weighed, and such a dose is 
injected that the heart will be found in complete systolic contraction 
at the end of exactly sixt} r minutes. The drug, properly diluted so 
as to make a volume of 0.5 to 1 c. c., is injected into the anterior lymph 
sac by means of a glass pipette. Shortly before the hour is up the 
frog is pithed, tied to a frog board, and the heart is exposed in the 
usual manner. If the heart is still beating, the dose has been too 
small and must be increased in subsequent trials. In the first series 
of frogs doses are chosen with wide limits, which in a second and 
third series of animals are narrowed down until the smallest amount 
of the drug which will produce systolic standstill in one hour is found. 
Usually three series of frogs are sufficient to assay one preparation, 
but in case of any irregularity in the reaction of any of the frogs a 
fourth or even a fifth series may be necessary. The results of our 
assay of the different preparations are given in Table V. 
Table V . — Determination of the systolic stoppage of the heart of Rana pipiens in one 
hour — Drug injected into abdominal lymph sac. The doses given are in cubic centi- 
meters per gram body weight. 
MULFORD NO. 1. B. W. AND CO. 
Number of animals used. 
Dose. 
Result. Number of animals used. 
Dose. 
| Result. 
1 
c. c. 
0.009 
.01 
.011 ; 
.0115 
.012 
.014 
.016 
- 1 
c. c. 
0. 018 
.019 
.020 
.020 
.021 
.022 
a + 
+ 
+ 
+ 
1. . 
- 1.. 
3 
- 1 
1 
— 1 
3 
+ 1 
1 
+ 1- 
1 
+ 
1 
DIGITALONE NO. 3. 
LLOYD BROS. 
1 
0. 027 
.028 
.029 
.030 
+ 
2 
0.035 
.037 
.038 
.039 
.040 
.040 
.041 
1 f\A O 
3 
3 
4 
1.... 
1 
1 
— DIGITALONE NO. 2. 
-4- 
1 
2 
i 
-SB 
, l 
0.025 
.032 
.040 
.090 
.105 
.120 
(») 
1 
| + l 
1 
S. AND D. 
1 
l 
l 
l 
1 
0.025 
.026 
.026 
.027 
.027 
.028 
.028 
.029 
- MULFORD NO. 2. 
1 
1 
+ 
— 1 
0. 014 
.015 
.016 
.016 
.017 
+ 
1 
3 
+ 2 
1 
' - 1. 
3 
+ 4 
1 
+ 1 
a Diastole. b Diastole, later beating. 
