A Touch of the Toxic, for Good or Ill

Vampire bat saliva and a zebra
longwing butterfly, devil’s gardens and
fossilized fish teeth, golden-frog
secretions and the sap of a manchineel
tree: Pity the poor witches of
Shakespeare’s “Macbeth” who had to
settle for “tooth of wolf” and “tongue of
dog.” Their boiling caldron makes an
appearance in an exhibition opening
Saturday at the American Museum of
Natural History — “The Power of
Poison “ — and so do they, black robed
and stirring the pot as green smoke
rises. But they don’t possess even a
fraction of the esoteric ingredients the
museum has assembled for this
elaborate show, nor do they have the
museum’s powers to brew something so
alluring out of such potentially grim
material.
The exhibition’s main curator is Mark
Siddall, from the museum’s division of
invertebrate zoology, who is currently
studying leeches’ venom (a perfect
ingredient for Shakespeare’s weird
sisters). He and the museum’s
accomplished team have combined
elements with deft curatorial alchemy,
touching on every taxonomical
category. We see Animal (including
diminutively cute, live orange frogs,
each of which secretes enough poison
on its skin to kill 10 humans); Vegetable
(including one of the world’s most
widely consumed plants, the cassava —
which is naturally laced with cyanide);
and Mineral (including amethyst
jewelry once worn to protect the
wearer from poison and Ammonite
fossils once thought to cure snake
bites). By the end, we even start
admiring poison’s possibilities and
warm to the idea of further immersion
— in the subject if not the substance.
This is also one of the most theatrical
exhibitions the museum has mounted in
recent years. You enter through mists
and vines evoking Colombia’s Chocó
forest. It is the habitat of those golden
frogs (Phyllobates terribilis), of hunters
who use blowguns and poisonous darts,
and of Giant Silkworm caterpillars,
whose hollow spines, we learn, can
pierce the skin and cause
uncontrollable bleeding.
At the center of the exhibition is a
theater in which, every half-hour, a
presenter uses mock lab equipment and
a slide show to demonstrate how
chemical tests were first used to detect
arsenic poisoning — and murder — in
the 19th century. The show regularly
gives the word “curtains” two
meanings.
The exhibition also has one of the most
effective high-tech displays I have seen.
A great book — 46 inches wide and 31
inches tall with heavy, parchmentlike
pages — is before us on a table. It
evokes a Medieval handwritten tome
exploring poisonous plants.
But the pages are screens for projected
images, and the illustrations respond to
the touch. Belladonna and hemlock
plants burst into bloom, accompanied
by explanations; drawings give way to
animations, showing, for example, why
rhododendron is known in some
regions as “goat-bane”: animals can
die from munching its leaves. As you
turn each enormous sheet, it goes
blank, and a new set of images coalesce
on the next page. The technology is
entirely in service to an aura of
antique magic (or its Harry Potterish
imitation).
And what poisonous visions — or
rather, visions of poison — begin to
take shape here? We generally think of
poison as something almost brutishly
forceful. But the exhibition turns it into
something far more mysterious.
Not even the sources of some poisons
are fully understood. Those secretions
of the small golden frogs? It turns out
that the creatures aren’t poisonous
when bred in captivity; the poison
develops because of something in their
natural diet, perhaps the “soft-winged
flower beetles” that are shown here. If
so, is that beetle associated with some
other danger the poison protects
against? No one yet knows.
Immunity to poison also has its
surprises. The manchineel tree from
the same Colombian forest, we learn,
has crab-apple-size fruits that can
swell the throat so breathing becomes
nearly impossible; its sap can cause
temporary blindness; even rainwater
dripping from the leaves makes the
skin blister. Manchineel sap poisoned
the arrow shot at the Spanish explorer
Juan Ponce de León after he landed on
the coast of Florida in 1521; he died “in
agony within days.” Yet iguanas
happily sleep in the tree’s branches and
eat its fruit.
The nature of a poison, then, can’t
really be understood without taking
into account the creature and the
habitat. We are shown a model of a
plant from South America in which
puffed hollow pods are seen below its
large leaves: nests for ants of the genus
Myrmelachista. The ants’ relationship
with the plant is so symbiotic; they
protect their nests by spraying a
poisonous acid at nearby plants of
competing species, killing them off,
creating a uniform patch — a devil’s
garden, it has been called — in the
midst of the forests of Peru and
Ecuador.
Poison, in this light, shapes an
environment. A video also shows how
predators and prey can end up
becoming part of a “biological arms
race,” in which poisons ratchet up their
strength as immunities expand in
intended victims.
But human society is a different story.
Here, poison is everywhere, and
evolution has nothing to do with it. In
a survey of myth and literature we
begin with a life-size diorama of those
three Shakespearean witches, many of
whose choice ingredients are toxic
plants: “Tooth of wolf” is wolfsbane;
“tongue of dog” is houndstongue. An
“Alice in Wonderland” display points
out that the “Mad Hatter” was a victim
of poisoning from mercuric nitrate, a
chemical once used in hat making. It
led to tremors and irritability. (An
American version of such poisoning,
which developed in Connecticut’s
hatmaking center, was known as the
“Danbury shakes.”) We see Snow White
in suspended animation (the neurotoxic
effects of puffer fish poison?) and the
Chinese Emperor Qin Shihuangdi
consuming mercury (it was meant to
guarantee his immortality, but it
ensured the opposite).
But the main purpose of poison in
human society, it seems, has been
murder. In France arsenic became
known as “inheritance powder” —
“poudre de succession.” Nero preferred
cherry laurel leaves when he was
dispatching an enemy. Agatha Christie
laced at least 28 mysteries with
poisons.
Finally, poison makes its way from the
world of literature and history to the
world of science. In a series of
investigations (also found in a free iPad
app developed by the museum), we are
presented with three puzzling illnesses
and asked to identify the poisons based
on the symptoms. Bright red gums,
tingling feet and a green liver are the
relevant clues.
But as poisons are studied more closely
by scientists they end up being
embraced, not shunned. A chemical
that so profoundly affects biological
processes may be dangerous, but it is
also a possible medication.
In fact, we learn, a chemical found in
the poisonous bark of the yew tree is
effective against cancer (leading to the
drug Taxol). One component of Gila
monster venom lowers the blood sugar
of its victims; it has been used to treat
Type 2 diabetes. The saliva of vampire
bats contains an anti-clotting agent
coyly called draculin, which may
protect against strokes. The venom of
pit vipers has led to blood pressure
drugs. And researchers are now testing
spider venom to develop treatments for
breast cancer.
There are things I wish the exhibition
had devoted more attention to,
particularly how poisons actually work
in the body. There were times, too,
where the exhibition seemed overly
cautious about morbidity, perhaps to
avoid frightening off its youngest
visitors. How, though, do you discuss
poison without giving a better sense of
its varied effects?
So some elements are left out. But who
needs an eye of newt or toe of frog
when you’ve already got such a
pungent brew? And so far, no ill
effects. ...