478 -—«~Prof. J. T. Cash and Dr. W. RB. Dunstan. [May 24, 
force. Though this statement applies in degree to direct as well as to 
indirect stimulation, the failure of the nervous intramuscular structures is 
relatively greater than that of the muscle fibre. 
After poisoning by as much as 0-007 to 0:008 gramme per kilogramme, 
entire absence of all response, even to direct stimulation applied 24 hours 
later, has been witnessed. Such a result is however exceptional. 
In order to test as closely as possible the actual and relative effects of 
indaconitine and spicaconitine upon nerve and muscle, immersion experiments 
were employed. MRinger’s perfusion solution was the menstruum used, this 
being well suited to the preservation of activity in nervous as well as in 
muscular tissue, as demonstrated by the fact that in control experiments 
in which 20 c.c. of this solution was used for immersing the muscle nerve 
preparation (the foot being retained as described in ‘ Phil. Trans.,’ B, vol. 195, 
p. 66), the nerve preserved its excitability for from 45 to 50, and the 
muscle for 75 to 86 hours. Accurately measured amounts of indaconitine 
and bikhaconitine solutions were tested on companion nerve-muscle prepara- 
tions obtained from the same animal, or else one of the preparations was 
exposed to an aconitine solution whilst the other was used as a control. 
In all cases the minimal excitability was determined from time to time with 
as little repetition of stimulation as possible. 
With solutions having a proportion of alkaloidal salt of 1/5000 to 1/25000, 
the effects of indaconitine and bikhaconitine are fairly parallel towards 
nervous as well as muscular tissue; but with solutions of 1/50000 and up to 
1/500000, indaconitine shows a somewhat greater activity relatively towards 
both structures, though the difference is more marked towards nervous 
tissue. The most dilute solution of indaconitine which proved directly 
active upon muscular tissue was 1/800000. 
Solutions of 1/1000000 indaconitine (which do not affect muscular tissue) 
abolish the contractility of the specimen indirectly stimulated four to five 
hours before parallel solutions of bikhaconitine do so, and even with 1/2000000 
the action of indaconitine usually preponderates, though but slightly. In a 
dilution of 1/2500000 bikhaconitine, the nerve muscle preparation frequently 
reacts as long as a control preparation to which no addition of an aconitine 
has been made. The excitability of intramuscular nerve structures is 
increased by both solutions when of medium attenuation, whilst the 
production by either of fibrillation is but seldom observed. 
The resistance of the nerve muscle preparations in this series taken from 
frogs very recently obtained, was greater than that of those used in the 
immersion experiments made with japaconitine and pseudaconitine, upon 
animals which had been some time in the laboratory. It has not been 
