366 THE SNAKES OF SOUTH AFRICA. 
rapidly induced in animals by introducing a few drops of Cobra 
venom into the fourth ventricle of the brain. 
Two DIsTINcT CLASSES OF VENOM. 
Although there is a difference in the action of the venom of 
each species of snake, we find there is a general similarity in the 
symptoms produced by the venoms of all snakes. 
The greatest difference is with the two families of venomous 
snakes, viz., the Colubrines and Viperines. The Colubrine snakes 
include our well-known Cobra, Ringhals and Mamba. The 
Viperines include all the Adders. These two families comprise 
all the very venomous South African snakes, with the exception 
of the Boomslang, which has only recently been shown to be a 
highly-venomous snake and which is classed in a sub-family of 
Colubrines. There is a marked difference in the symptoms pro- 
duced by Colubrine venom and Viperine venom. 
ACTION OF COLUBRINE VENOM. 
Colubrine (Cobra family) venom acts directly and speedily 
upon the nervous system. Viperine venom is slower, and 
operates both upon the nervous system and blood. If a fatal 
dose of Cobra venom be injected direct into a vein, it is speedily 
carried to the heart, instantly stopping the action of that organ, 
and causing death in a few moments. A dose injected into a 
vein in the thigh of a dog caused instant death. This effect, 
however, is only produced when the venom is injected direct into 
the veins. When Cobra venom is injected into the tissues, as 
invariably happens in ordinary cases of snake bite, the poison is 
absorbed less rapidly, and instead of stopping the heart’s action: 
it has a contrary effect, stimulating it into increased activity. 
The venom acts directly upon the nervous system, causing 
gradual cerebro-spinal paralysis. Ifa fatal dose has been intro- 
duced and absorbed into the blood, the nerves controlling the 
automatic action of the lungs are paralyzed, and breathing 
ceases, although the heart is unaffected and continues beating 
for some minutes, which clearly shows its vasomotor nerve 
centres are unaffected by the venom. The lungs having ceased 
