ON HYDROCYANIC ACID 
315 
muscles, and rapidly followed by all the motor muscles. I have 
always believed that the effect has been more upon the motor fibres 
than upon the sensitive fibres of the nerves. The first effect upon 
the muscular system is seen in the voluntary and partially involun- 
tary muscles, the heart, and respiratory system, the heart flutter- 
ing rapidly, beating to 120 or more ; the abdominal muscles vio- 
lently contracted ; great expansion of the nostrils, though but a 
very small volume of air passes through them ; great heaving of 
the ribs, but not of the flanks, which are very tremulous. Then 
follows the voluntary muscles; excitement of the limbs, shaking of 
the tail, violent efforts to rise, and falling again with great force ; 
the eyes drawn violently inwards and upwards by the internal 
oblique muscles; contraction of the iris; profuse perspiration. 
These various symptoms shew themselves very nearly as I have 
placed them, but they are all manifested with such rapidity that it 
is difficult to assign them their proper order. The cessation of 
symptoms is the reverse of the accession : 1st, voluntary mus- 
cles; 2d, partial involuntary muscles; 3d, involuntary muscles; 
relaxation of the constricted muscular fibre; gaspings; coma; 
quivering of the eyes ; hanging of the lips ; insensibility ; death. 
From the time of administration to the greatest intensity of 
effect I have found to vary from not less than ten and not more 
than twelve or thirteen minutes. Thence to the cessation of all 
vital functions an equal period elapses, so that the actual time 
which is requisite to destroy life may be concluded to be not less 
than twenty or more than twenty-six minutes. This I have found 
in all the cases in which I have administered it to horses in ordinary 
health. 
To the dog I gave two drachms of acid, and the symptoms were 
as nearly as possible similar, with the addition of horrible howl- 
ings; and the period from the administration of the poison until 
death was fifteen minutes, divided as beforementioned. 
I am also led to suppose that there is greatly diminished sensi- 
bility throughout. 
The other two cases have now to be considered ; they are both 
different to those above detailed, and also different to each other. 
The first was a small horse with defective vision, which was being 
ridden by a lad with only a halter on the horse’s head, and while 
going at a fast trot came in contact with the wheel of a cart, knock- 
ing down the horse, which laid insensible : — he was drawn into 
the stable of an inn at hand. Upon my seeing the animal, which 
as well as I could ascertain was nearly an hour after the accident, 
he was lying on the off side ; pupils much dilated ; stertorous 
breathing ; power and sensation impaired in the fore and lost in 
the hinder extremities. The symptoms were so decidedly those of 
