354 poisons : their effects and detection. [§§ 419, 420. 
time it assumes a pinkish hue, and if warmed on the water.-bath, a more or less 
purple colour ; if a small crystal of potassic bichromate be slowly stirred in the 
sulphuric acid solution, reddish-purple streaks are produced along the path of the 
crystal ; ceric oxide exhibits this better and more promptly, so small a quantity as 
•001 grain showing the reaction. This reaction is something like that of strychnine, 
but nitric acid causes gelsemine to assume a brownish-green, quickly changing to 
deep green—a reaction which readily distinguishes gelsemine from strychnine and 
other alkaloids. 
§ 419. Fatal Dose. — 10 mgrms. killed a frog within four hours, and 8 mgrms. a 
cat within fifteen minutes. A healthy woman took an amount of concentrated 
tincture which was equivalent to 11 mgrms. (| grain), and died in seven and a half 
hours. 
§ 420. Effects on Animals.—Physiological Action. —Gelsemine acts powerfully 
on the respiration ; for example, Drs Sydney Ringer and Murrell 1 found, on operating 
on the frog, that in two minutes the breathing had become distinctly slower ; in 
three and a half minutes, it had been reduced by one-tliird ; and in six minutes, by 
one-half ; at the expiration of a quarter of an hour, it was only one-third of its 
original frequency ; and in twenty minutes, it was so shallow and irregular that it 
could no longer be counted with accuracy. In all their experiments they found 
that the respiratory function was abolished before reflex and voluntary motion had 
become extinct. In several instances the animals could withdraw their legs when 
their toes were pinched, days after the most careful observations had failed to detect 
the existence of any respiratory movement. The heart was seen beating through 
the chest wall long after the complete abolition of respiration. 
In their experiments on warm-blooded animals (cats), they noticed that in a few 
minutes the respirations were slowed down to 12 and even to 8 , and there was loss 
of power of the posterior extremities, while at short intervals the upper half of the 
body was convulsed. In about half an hour paralysis of the hind limbs was almost 
complete, and the respiratory movements so shallow that they could not be counted. 
In the case of a dog, after all respiration had ceased tracheotomy was performed, and 
air pumped in : the animal recovered. 
Ringer and Murrell consider that gelsemine produces no primary quickening of 
the respiration, that it has no direct action on either the diaphragm or intercostal 
muscles, that it paralyses neither the phrenic nor the intercostal nerves, and that it 
diminishes the rate of respiration after both vagi have been divided. They do not 
consider that gelsemine acts on the cord through Setschenow's inhibitory centre, but 
that it destroys reflex power by its direct action on the cord, and that probably it 
has no influence on the motor nerves. Dr Burdon Sanderson has also investigated 
the action of gelsemine on the respiration, more especially in relation to the move¬ 
ments of the diaphragm. He operated upon rabbits ; the animal being narcotised 
by chloral, a small spatula, shaped like a teaspoon, was introduced into the peri¬ 
toneal cavity through an opening in the linea alba, and passed upwards in front of 
the liver until its convex surface rested against the under side of the centrum tendi- 
neum. The stem of the spatula was brought into connection with a lever, by means 
of which its to-and-fro movements (and consequently that of the diaphragm) were 
inscribed. The first effect is to augment the depth but not the frequency of the 
respiratory movements ; the next is to diminish the action of the diaphragm both in 
extent and frequency. This happens in accordance with the general principle applic¬ 
able to most cases of toxic action—viz. that paresis of a central organ is preceded 
by over-action. The diminution of movement upon the whole is progressive, but 
this progression is interrupted, because the blood is becoming more and more venous, 
and, therefore, the phenomena of asphyxia are mixed up with the toxic effects. Dr 
Sanderson concludes that the drug acts by paralysing the automatic respiratory centre ; 
the process of extinction, which might be otherwise expected to be gradual and pro¬ 
gressive, is prevented from being so by the intervention of disturbances of which the 
explanation is to be found in the imperfect arterialisation of the circulating blood. 
1 Lancet, 1876, i. 415. 
