482 Prof. J. T. Cash and Dr. W. R. Dunstan. [May 24, 
6. Up to 180’ there is usually summation of bikhaconitine effect after 
a 0'5 lethal dose, whereas summation after indaconitine for a parallel proportion 
is rarely witnessed after a longer interval than two hours. 
Action of Bikhaconitine towards Frogs (R. temporaria). 
(A Synopsis of Experiments is appended.) 
0:0009 gramme per kilogramme.—Excitement, then voluntary movement 
reduced, limb reflexes often uncertain, respiration slowed, ultimately 
suspended. 
0:0012.—Excitement, with frothing on the body. After transitory accele- 
ration, slowing and arrest of respiration, all voluntary movement disappearing, 
gaping movements, great impairment of reflexes, lasting 4 to 5 days, during 
which period there is inability to get off the dorsal position. 
0:0013.—As above; but cardiac irregularity develops, with ultimate failure 
of effective systole, the circulation in the web becoming partial, feeble, and 
intermittent until it ceases altogether. Death takes place in 12 to 14 hours 
after injection. 
Lethal Dose-—In June and July an occasional lethal effect followed a pro- 
portion of 0°001 gramme and upwards, until on reaching 0:00125 gramme 
per kilogramme recoveries were very exceptional. The last may be accepted 
as the lethal proportion. 
Whilst the action of bikhaconitine is both qualitatively and quantitatively 
closely similar to that of indaconitine on the heart, the effect of bikh- 
aconitine is greater than that of indaconitine on the frog’s respiration. 
Action on Respiration.—Suspension of respiration is not essentially inimical 
to the continuance of life in frogs, and therefore, though bikhaconitine causes 
an arrest of visible or registrable movement in smaller proportion than ind- 
aconitine would, the lethal proportion is practically the same for the two 
alkaloids. Whilst proportions of 0:0008 to 0:0009 of bikhaconitine may 
suspend respiratory movement for from 14 to 23 hours, doses approaching 
the lethal prolong the period of inactivity to 36 hours or more. 
Bikhaconitine upon the Cardiac Rhythm of Frogs.—The eftects of this 
alkaloid are essentially those of indaconitine, as are also the modifications 
produced in the reaction of the heart to vagus stimulation. 
Perfusion of the separated organ has also parallel results. Fig. C2, C3 shows 
the increased excitability, accelerated rhythm, and failing systole of the 
ventricle under perfusion of relatively powerful solutions of the alkaloid 
(000048 and 0:000549). The two contractions in C, are elicited by stimula- 
tion before circulation of bikhaconitine. 
