278
FINDLAY E. RUSSELL
into three types : the volvent type, in which the tube end is closed ;
the penetrant type, in which the tube end is opened ; and the glutinant
type, in which the tube is open and sticky. The volvent type is unarmed; its threads, when discharged, wrap around and entangle the
bristles or fibers of the offending animal. The penetrant type is armed
with spiralling rows of spines which serve in anchoring the thread to
the object of attack. The point of the thread is capable of penetrating
certain epithelial tissues, and venom may be discharged through its
open end into the wound. The piercing ability of some penetrants is
sufficient to puncture the chitinous cuticles of several marine animals.
The glutinant type of nematocyst appears to respond only to mechanical
stimuli and may be used by a cnidarian for anchoring its tentacles
during locomotion.
B . Chemistry and toxicology
As with many of the earlier studies on venoms, the initiating
investigations on the chemical and toxicological properties of cnidarian
venom were carried out with crude saline or water extracts prepared from the whole animal, or from one or several of its parts.
The findings from these studies were subject to considerable variation,
and the reports in the literature of those years reflect the uncertainty
of the chemical analyses. It is apparent that some of these early
workers were studying normal constituents of the animal’s tissues,
some of which are limited to the lower phyla. While these constituents
are not toxic to the animals of the lower phyla they may produce
deleterious effects in higher animals. During more recent years it has
been possible to isolate specific nematocysts from cnidarians so that
at the present time most investigators are working with either a highly
concentrated extract from nematocysts or with the material discharged
from the nematocysts following electrical stimulation.
Just after the turn of this century, Richet (1906) and his colleagues
separated three pharmacologically active fractions from the tentacles
of Actinia, which when injected into dogs produced scratching, pulmonary edema or sedation. These fractions were named “ thallasin ”,
“ congestin ” and “ hypnotoxin ”. [The phenomenon of anaphylaxis
was discovered during certain of these studies on cnidarian toxins
(Richet and Portier, 1936).] These substances were not specific compounds but rather mixtures having deleterious biological effects.
Thallasin has been shown to induce the release of histamine in tissues,
and following its intravenous administration in the cat causes the
appearance of a “ slow contracting substance ” in the plasma (Jaques
and Schachter, 1954).
FINDLAY E. RUSSELL
into three types : the volvent type, in which the tube end is closed ;
the penetrant type, in which the tube end is opened ; and the glutinant
type, in which the tube is open and sticky. The volvent type is unarmed; its threads, when discharged, wrap around and entangle the
bristles or fibers of the offending animal. The penetrant type is armed
with spiralling rows of spines which serve in anchoring the thread to
the object of attack. The point of the thread is capable of penetrating
certain epithelial tissues, and venom may be discharged through its
open end into the wound. The piercing ability of some penetrants is
sufficient to puncture the chitinous cuticles of several marine animals.
The glutinant type of nematocyst appears to respond only to mechanical
stimuli and may be used by a cnidarian for anchoring its tentacles
during locomotion.
B . Chemistry and toxicology
As with many of the earlier studies on venoms, the initiating
investigations on the chemical and toxicological properties of cnidarian
venom were carried out with crude saline or water extracts prepared from the whole animal, or from one or several of its parts.
The findings from these studies were subject to considerable variation,
and the reports in the literature of those years reflect the uncertainty
of the chemical analyses. It is apparent that some of these early
workers were studying normal constituents of the animal’s tissues,
some of which are limited to the lower phyla. While these constituents
are not toxic to the animals of the lower phyla they may produce
deleterious effects in higher animals. During more recent years it has
been possible to isolate specific nematocysts from cnidarians so that
at the present time most investigators are working with either a highly
concentrated extract from nematocysts or with the material discharged
from the nematocysts following electrical stimulation.
Just after the turn of this century, Richet (1906) and his colleagues
separated three pharmacologically active fractions from the tentacles
of Actinia, which when injected into dogs produced scratching, pulmonary edema or sedation. These fractions were named “ thallasin ”,
“ congestin ” and “ hypnotoxin ”. [The phenomenon of anaphylaxis
was discovered during certain of these studies on cnidarian toxins
(Richet and Portier, 1936).] These substances were not specific compounds but rather mixtures having deleterious biological effects.
Thallasin has been shown to induce the release of histamine in tissues,
and following its intravenous administration in the cat causes the
appearance of a “ slow contracting substance ” in the plasma (Jaques
and Schachter, 1954).