EFFECT OF SNAKE VENOM UPON THE NERVOUS SYSTEM, ETC. 127 
longer transmit to the muscles of respiration the ordinary stimuli from the 
medulla, they can still transmit those stronger impulses which proceed from 
it when greatly stimulated by the increasing venosity of the blood, and which 
cause the respiratory as well as the other muscles of the body to participate 
in the general convulsions. Experiments show that the peripheral termina- 
tions of the motor nerves are actually paralyzed by cobra venom. Here 
special attention is drawn to the striking parallelism between the effects 
produced by cobra venom and those by curare upon the nerve-endings. 
Brunton and Fayrer describe also the paralysis of the spinal cord by cobra 
venom. One of the typical experiments which led these authors to demon- 
strate the paralysis of motor-nerve endings after the injection of cobra venom 
was made by protecting one sciatic nerve from the action of the venom (in 
frog) by means of cutting off all its circulation, and by testing the electric 
irritability of the protected and unprotected nerves after apparent paralysis. 
They always found that the side which had been protected from the effects 
of the venom gave a ready reaction to the stimulus, but that the unpro- 
tected sciatic nerve failed to produce contraction of the muscles. Naturally 
the irritability of the protected sciatic nerve did not react as strongly as 
the control, but this was easily explained by the fact that the nerve in the 
former frog was for some time deprived of its blood supply. The direct 
stimulus to the muscles themselves shows that their excitability was well 
retained both in protected and in unprotected legs. It was also seen that 
the longer and nearer the contact of the nerve-endings with a stronger con- 
centration, the more complete is the paralysis of the nerve-endings. 
In regard to the effects of cobra venom upon the spinal cord, both on 
warm-blooded animals and frogs, Brunton and Fayrer concluded that the 
gray matter is paralyzed, since there is no transmission of painful impulses; 
but the white sensory columns are little, if at all, affected. The power of the 
cord to conduct motor impressions from encephalic ganglia appears to be 
little, if at all affected, until the apparent death of the animal, and they found 
that, very shortly before respiration ceased, and when ordinary reflex action 
from the cord was nearly gone, voluntary movements were still made. 
According to Brunton and Fayrer the sensory nerves seem to be little, if at 
all, affected by cobra venom. In contrast to the quick paralysis of the motor 
nerves of the poisoned limbs the irritability of the sensory nerves is long 
retained. In an experiment the irritability of the optic nerve and the aural 
and buccal branches of the trigeminus was seen to be present after the cord 
had become nearly paralyzed, and in several experiments reflex actions could 
be induced by irritation of the cornea after voluntary motion and respiration 
had ceased. 
The effects of cobra venom upon secretory nerves have also been mentioned 
by Brunton and Fayrer, who were uncertain as to the exact mechanism 
effecting profuse salivation in cobra poisoning in dog. The possibilities were 
open either to the direct or to the indirect stimulation on the secretory nerves. 
Judging,from the simultaneous occurrence of nausea and vomiting, they were 
