EFFECT OF SNAKE VENOM UPON THE NERVOUS SYSTEM, ETC. 129 
endings is found to be much quicker than that of the muscles themselves. 
In order to produce a fuller effect of the venom upon the musculo-endings 
he advises the employment of a weak solution or about 0.0000333 gm. (or 
1/30 mg.), 0.00005 gm. being a minimal lethal dose, for injection into the 
dorsal lymph-sac of frogs; too large an amount kills the animal directly 
from general paralysis without much curare-like action on the nerve endings. 
He confirms the theory that the phrenic nerves are affected much earlier 
than other motor nerves. 
Ragotzi did not observe acceleration of respiratory frequency at any stage 
of the poisoning. The inhibitory end-plates of the vagus in the heart were 
unaffected. In some animals the venom caused a rapid, transient weaken- 
ing of the heart, which, however, regained its original activity very soon. 
In the frog, when the venom is given intravenously it arrests the heart in sys- 
tole at once, and Ragotzi considers this to be due to the direct effect upon 
the cardiac muscle. In the case of subcutaneous injection, the heart stops in 
diastole, due, according to this author, to the paralysis of the cardiac ganglia. 
Ragotzi emphasized that the spinal cord is not directly affected by cobra 
venom, and that insensibility of the muscles to the stimuli through the spinal 
cord is in most cases due to the end-plate paralysis of the motor nerves; 
or, if there is any paralysis in the cord, it is of a secondary nature, chiefly due 
to the insufficient blood supply caused by the venom. He recalls the possi- 
bility of a fatal hemorrhage or thrombosis occurring in the regions of the 
nerve centers when the fresh venom is employed. 
Elliot, Sillar, and Carmichael’ found the effects of the venom of Bungarus 
ceruleus, the common krait, on the nervous system to consist of paralysis 
of the respiratory center, curare-like action on the nerve-endings, especially 
affecting early those of the phrenic nerves, and dilatation of the splanchnic 
vessels. ‘The vasomotor center is strongly affected. The contraction of arte- 
rioles and capillaries is produced, but not in so marked a degree as in the 
cobra poisoning. 
Wall, and later Lamb,? made many important contributions to our knowl- 
edge of the behavior of the venom of Bungarus fasciatus (banded krait). 
In acute cases of poisoning death invariably came through respiratory failure, 
with very pronounced paralysis of the limbs. In intravenous injection death 
took place much earlier than in the case of subcutaneous administration of 
the venom. Lamb is inclined to attribute the cessation of respiration to 
paralysis of the respiratory center, but no effort has been made to ascertain 
the extent to which the nerve-endings of certain motor nerves — especially 
the phrenics —are affected. The changes produced by this venom in the 
nervous system are chiefly chromatolytic degeneration throughout the entire 
cerebro-spinal system. I intend to return to this more in detail in a later 
section. 
Leer ae Ce ee ee ee 
1 Elliot, Sillar, and Carmichael. On the action of the venom of Bungarus ceruleus (the common krait). 
Roy. Soc. Proc., 1904, LX XIV, 108. 
2Lamb. Some observations on the poison of the banded krait (Bungarus fasciatus). Sci. Mem. by 
Officers of the Med. and Sanit. Depts. of the Govern. of India, 1904, new series, No. 7. 
