298
FZNDLAY E. RUSSELL
found that as little as one thousandth of the total venom from one
specimen of C. textile was lethal to C. californicus. I n one species of fish,
0.2 mm3 of the venom duct contents of C. striatus was lethal, while in
mice the lethal dose was approximately 0-2 mg of venom duct content.
The lethal dose varies not only with the species involved but
also with the area of the duct from which the extract is prepared.
The contents of the posterior half of the duct in most species so far
examined appear to be far more toxic than the contents from the
anterior half. I n mice, Endean and Rudkin (1965) found that C.
geographus and C. magus venoms were lethal at 0.2-1.3 mg/kg body
weight, while the minimal lethal dose for C. striatus venom was 21
mg/kg, and for C. stercusmuscarius venom, in excess of 200 mg/kg.
I n blennies they found the LD,, for the venom from the posterior
duct of C. striatus to be 0.4 mg/kg, while the minimum lethal dose
for C. stercusmuscarius venom was approximately 1.0 mg/kg. The
minimal lethal dose of anterior duct venom from the latter cone was
3.0-28.0 mg/kg of blenny.
When Conus venoms toxic to mice are injected a syndrome develops
which indicates that the venom has a particular effect on this animal's
nervous system. Such signs as muscular weakness, changes in the deep
reflexes, tremors, convulsions, ataxia, and paralysis of the skeletal
muscles are sometimes seen. Respiratory rate is usually affected and
complete cessation of respirations leading to death occurs in the more
seriously poisoned animals. Increased parasympathetic activity may
sometimes be observed following the injection of some Conus venoms.
Signs related to 'the gradual development of cardiac failure may be
evident in the more seriously poisoned mice.
Fishes injected with certain Conus venoms display radical alterations in their stance and swimming movements, erection of their fins,
blanching, respiratory changes and muscular paralysis. Gastropods
poisoned by the toxin often retract, sometimes violently, into their
shells. Subsequently, when they are withdrawn, they appear to be
paralyzed. Some may try to climb a wall of their tank only to fall to
the bottom when paralysis occurs.
It would appear that the principal activity of the venom is directed
toward the peripheral nervous system, although there is good evidence
of some direct central nervous system involvement. Whyte and Endean
(1962) have shown that venom from the posterior half of ducts of
C . geographus blocks conduction in the mammalian phrenic nervediaphragm preparation, and causes paralysis of isolated skeletal muscle.
C. textile venom did not produce these changes.
Extracts lethal to mammals have been prepared from the venom
FZNDLAY E. RUSSELL
found that as little as one thousandth of the total venom from one
specimen of C. textile was lethal to C. californicus. I n one species of fish,
0.2 mm3 of the venom duct contents of C. striatus was lethal, while in
mice the lethal dose was approximately 0-2 mg of venom duct content.
The lethal dose varies not only with the species involved but
also with the area of the duct from which the extract is prepared.
The contents of the posterior half of the duct in most species so far
examined appear to be far more toxic than the contents from the
anterior half. I n mice, Endean and Rudkin (1965) found that C.
geographus and C. magus venoms were lethal at 0.2-1.3 mg/kg body
weight, while the minimal lethal dose for C. striatus venom was 21
mg/kg, and for C. stercusmuscarius venom, in excess of 200 mg/kg.
I n blennies they found the LD,, for the venom from the posterior
duct of C. striatus to be 0.4 mg/kg, while the minimum lethal dose
for C. stercusmuscarius venom was approximately 1.0 mg/kg. The
minimal lethal dose of anterior duct venom from the latter cone was
3.0-28.0 mg/kg of blenny.
When Conus venoms toxic to mice are injected a syndrome develops
which indicates that the venom has a particular effect on this animal's
nervous system. Such signs as muscular weakness, changes in the deep
reflexes, tremors, convulsions, ataxia, and paralysis of the skeletal
muscles are sometimes seen. Respiratory rate is usually affected and
complete cessation of respirations leading to death occurs in the more
seriously poisoned animals. Increased parasympathetic activity may
sometimes be observed following the injection of some Conus venoms.
Signs related to 'the gradual development of cardiac failure may be
evident in the more seriously poisoned mice.
Fishes injected with certain Conus venoms display radical alterations in their stance and swimming movements, erection of their fins,
blanching, respiratory changes and muscular paralysis. Gastropods
poisoned by the toxin often retract, sometimes violently, into their
shells. Subsequently, when they are withdrawn, they appear to be
paralyzed. Some may try to climb a wall of their tank only to fall to
the bottom when paralysis occurs.
It would appear that the principal activity of the venom is directed
toward the peripheral nervous system, although there is good evidence
of some direct central nervous system involvement. Whyte and Endean
(1962) have shown that venom from the posterior half of ducts of
C . geographus blocks conduction in the mammalian phrenic nervediaphragm preparation, and causes paralysis of isolated skeletal muscle.
C. textile venom did not produce these changes.
Extracts lethal to mammals have been prepared from the venom