56 Transactions of the Royal Society of South Africa. 
Experiments on Xenopus laevis : 
Ext. 
of toad. 
Time. 
Result. 
1. 
"001 mg. 
25 min. 
Death. 
2. 
•0009 „ 
54 „ 
3. 
•0008 „ 
70 „ 
4. 
0007 „ 
135 „ 
5. 
•0006 „ 
Recovery. 
6. 
•0005 „ 
7. 
8. 
9. 
•0007 „ 
•0007 „ 
•0007 „ 
80 min. 
130 „ 
Overnight. 
Death. 
10. 
•0007 „ 
Recovery. 
11. 
•0006 „ 
12. 
•0006 „ 
This would show that the minimal lethal dose of this strophanthin for 
the toad is 0007 mgrm. per gramme, practically the same as for Bana 
temporaria. 
Minimal Systolic Dose of Tinctures (B.P.). 
Two freshly prepared tinctures of digitalis and one of squills were 
tested by the same method. At the end of one hour the toads were pithed 
and the condition of the heart examined. The tinctures were known to be 
active, in two cases by estimating the minimal lethal intravenous dose for 
cats, and in the other by subsequent clinical trial. 
The minimal systolic doses of the tinctures of digitalis were '0055 c.c. 
and 005 c.c. per gramme of toad, and of the tincture of squills - 006 c.c. per 
gramme. These figures are in close agreement with what would have been 
expected with Bana temporaria, in which an accepted standard of activity 
of these tinctures is a minimal systolic dose of 0*006 c.c. per gramme. 
From these experiments it is concluded that Xenopus laevis is as 
susceptible as Bana to the action of the digitalis group, and that it may be 
used like Bana for the biological assay of digitalis preparations, the doses 
for both being the same. 
References. 
(1) Vulpian.— 'Compt. Rend. Soc. Biol.,' ser. 2, i, 1854, p. 133. 
(2) Abel and Macht. — ' Journ. Pharm. Exper. Therap.,' iii, 1912, p. 319. 
