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The Proving Of Didelphis Virginiana – The Virginia Opossum

Last modified on September 8th, 2012

Susan Sonz
Written by Susan Sonz

A full proving of the Virginia Opossum by the New York School of Homeopathy.


The homeopathic community has recently suffered the loss of two very important contributors; David Kent Warkentin and Michael Quinn.  David’s visionary creation of MacRepertory and ReferenceWorks has inspired a revolution in modern homeopathic thinking and practice. David changed homeopathy for everyone, forever. Today’s innovative and progressive work in homeopathy would not be possible without his ingenious software programs. His gentle spirit and sweet smile will be sorely missed by all of us who knew him.

Michael Quinn, founder of Hahnemann Laboratory and Pharmacy, was among the most loved and respected figures in modern homeopathy.  Besides being an innovator of pharmacy procedures, Michael was a leader in the scientific study of homeopathy.  For many years he generously assisted homeopathic provings by creating the remedies from the original substance. Michael leaves a legacy of great dedication and integrity in his field and in his life.

Modern homeopathy has been profoundly influenced and advanced by of the work of these two men.  Their achievements will live on, as we remember their enthusiasm for homeopathy and their invaluable contributions to our wonderful profession.


Scientific Classification

Kingdom: Animalia

Class: Mammalia

Infraclass: Marsupialia (the only North

American Marsupial)

Phylum: Chordata

Order: Didephimorphia (Gill, 1872)

Family: Didelphidae (Gray, 1821)

Male: Jack

Female: Jill

Young: Joey

Didelphis – Means “double womb”.

Virginiana – From the State of Virginia, where the opossum was first observed and described by explorer John Smith, in Map of Virginia, with a Description of the Countrey, the Commodities, People, Government and Religion, written in 1608.

Opossum – From the Native American “apasum” meaning “white animal”. Often referred to colloquially as “possum”, this usage properly refers to the closely related Australian variety.

Remedy Name: Sanguis Didelphis Virginiana

Available From: Hahnemann Laboratory & Pharmacy

1-888-427-6422 www.hahnemannlabs.com

Obtaining The Source

Inspiration for this proving came from a client in the NYSH student clinic who had told us of a vivid and unusual vision; a drunken opossum (who had eaten compost from wine-making refuse) was dancing on the roof of her garage.

Once research began, many intriguing features came to light such as the opossum’s unique reaction to stress (“playing possum” – an involuntary, coma-like state), its unusual immune system, and its prolific fertility.  These features, amongst others, led us to believe opossum to be a good subject for a proving.

Our opossum was humanely trapped in an urban location on Long Island, New York.  It had been coming to eat cat food put out on someone’s porch and was captured by Jeffrey Gatz from Bioreclamation Inc., using cat food as bait.

Capture occurred between the hours of 11:00 pm and 6:00 am on Aug 2nd -3rd, 2008.  The source animal was a young adult lactating female in good health although on the thin side, presumably from nursing.  There was no evidence of young on or about her at the time of capture. There was no obvious evidence of disease, illness or injury.

She did not “play possum” at any time and was described by Jeff as being “pretty calm” throughout her capture and captivity.  She was given fresh food and water during her captivity, and was released once blood had been drawn.  Jeff used a standard ACD vacutainer to collect the blood (ACD is an anti-coagulant).  It was then flown to the Hahnemann Laboratory and Pharmacy in California where Michael Quinn and Sonya Sakaske, made the remedy for us.

Natural History


The order Didelphimorphia includes only New World marsupials, which are all species of opossum.  Opossum appear in the North American fossil record as far back as 100 million years ago.  Sixty-six species of Didelphimorphia exist in the New World; eleven species of opossum reached as far north as Central America and only one, the Virginia Opossum, is found in North America.

The opossum is a marsupial.  Marsupial mammals differ from placental mammals in that female marsupials have a fur-lined pouch (marsupium) on their abdomens.  Young are born in an embryonic state after a very short gestation period of just 12-13 days, and complete their development attached to a nipple inside the mother’s pouch.

Marsupials have a skeletal system closer to that of reptiles.  They have a less efficient reproductive process and a more primitive brain than placental animals.  The opossum’s brain is a third to half the size of other mammals of similar size, and is primitive in structure.  Results of some learning and discrimination tests show that, in spite of their brain size, opossum are above dogs an on par with pigs in regards to intelligence.

Physical Characteristics

The opossum is a placid and shy omnivore approximately the size of a house cat.  Generally slow moving, opossum are primarily nocturnal.  They usually weigh between 4-12 lbs., and measure between 15-24 inches long (not including their tails).  Males are larger and weigh about a third more than females.

The opossum has an elongated snout, a pink nose, black eyes, and black ears.  Typically, the face is covered in white fur and the body fur is primarily grayish white, shading to a dark grey on its legs.  The Virginia Opossum is unique in its coloration; the body has white-tipped guard hairs that give it a grizzled appearance.  The further south they live the darker their coloration becomes.  Opossum often show signs of frostbite on their ears and tail because these body parts have no hair to protect them.

They have 50 teeth – more than any other land mammal.  Research has established that they are one of the few mammals, other than humans, to have color vision.  In addition, they have very good night vision.

Their hairless, prehensile tail is used like an extra “hand” to carry nest- building materials to their den site and to facilitate movement through trees and brush.  While young opossum may be able to hang upside-down for a short period of time by their tails, they quickly become too heavy to be able to do this as adults.  It is a myth that they sleep this way.

The legs of the opossum are short.  They have a plantigrade gate, meaning they are flat-footed, walking with the entire sole of their foot on the ground.  Their hind feet have a “halux” – an opposable thumb-like appendage.  This makes their five-fingered, tracks very distinctive and easily recognizable.  Their fingers are very dexterous, like those of a raccoon (with which they share habitat requirements).

Opossum have the shortest lifespan of any animal of comparative size.  Sources disagree on the exact figure, but most claim an average lifespan in the wild of only 2-3 years.  They don’t live much longer in captivity.  Males have a higher mortality rate than females because they range further, making them more likely to fall prey to predators or run afoul of motor vehicles.

Range and Habitat

The Virginia opossum is commonly found throughout southeastern Canada, through the Eastern United States and into Costa Rica.  They were introduced into California, parts of Arizona, Western Colorado and Idaho.  In recent years, opossum have been extending their range northwards as winters have become more moderate.

Opossum are both terrestrial and arboreal.  They have a varied habitat but prefer low, damp woodlands near permanent bodies of water such as lakes, ponds, streams or rivers.  They are known to be strong swimmers if necessity forces them to it.  As they roam their territory, they tend to follow water courses, making their ranges elongate rather than circular.

Opossum are solitary and nomadic, staying in a home range for as long as the food supply lasts before moving on to new territory.  A home range is between 15-40 acres but this varies greatly according to the geography.  Individuals may wander widely, especially in the fall.  Males tend to range farther than females.  Individual ranges overlap and they tend to be tolerant of neighboring individuals, but they will defend the area they are occupying at any given time.


The complexity of the placental mammal’s social system is much greater than that of the marsupials.  Opossum, even young ones, don’t play or interact much and are generally pretty lethargic.

Males are usually aggressive towards other males but rarely towards females.  Females tolerate each other (except when in heat) and some sources claim they may even live communally.  They generally do not tolerate males except when sexually receptive.

Opossum are primarily nocturnal but may become active during the day in warm weather when females need to forage more if they are pregnant or nursing.  During bad weather or extreme cold, opossum may remain in their nests or dens for several days at a time but they do not hibernate.  Because they don’t store food and their body reserves aren’t that extensive, they must forage on a regular basis, even during extreme weather conditions.

Den sites include hollow trees, fallen logs, piles of brush, and the abandoned nests and burrows of other animals – anywhere that’s dry, sheltered and safe.  They will also take advantage of human made “dens” under porches, in attics, chimneys, etc.  Opossum have been known to den in groups and even share a winter den with rabbits, skunks, raccoons and woodchucks.

Opossum find different daytime dens or nests as they wander their territories for food.  Even pregnant and nursing females will not keep a regular den.  This is highly unusual behavior for a mammal.  But, because the young travel in the mother’s pouch, she is free to continue in her nomadic ways throughout the birth and rearing of her young.

Opossum wash their faces with their front paws like a cat does.  They also use their hind “thumb” as a handy grooming aid.  Females pay particular attention to grooming their pouch, particularly if young are present.

They have a vocal repertoire consisting of hisses, growls and screeches when they are threatened.  They also make a metallic “click” used in a variety of situations, including mating, and in aggressive encounters.  Young will make a “chuff” or sneezing kind of sound if they become separated from their mothers and she will “click” back to them.

Playing Possum

Opossum are most famous for feigning death or “playing possum”.  They are very slow runners and usually try to escape predators by climbing the nearest tree.  But, when faced with a danger it can’t easily escape, the opossum will first bare all fifty of its teeth, hiss and growl.  It may lunge at the predator or try to run away.  If this fails, it may then fall onto its side, drool, defecate and exude a foul smelling green substance from its anal glands located on either side of the cloacal vent.  This serves to make it very unattractive to the predator that may have been threatening them, as many predators prefer live prey.  Unfortunately this strategy has no effect on motor vehicles

This catatonic state is largely an involuntary stress reaction which may last for minutes or even hours (like fainting in humans).  In this state, their heart rate has been recorded to drop by 46 percent and their respiration rate to drop by 30 percent.  The animal can be poked, prodded, even picked up and moved about without reviving.  Yet, when the danger is past, the animal somehow revives itself and resumes its normal activities.

One source claims that only about 10% of opossum under study exhibited this death feigning behavior.  In addition, the shock that initiates this state had less effect each successive time it was applied until, by the third or fourth trial, the opossum showed no signs of impact at all.[1]


Opossum have a primitive and bifurcated (“forked”) reproductive system.  Males have a forked penis and females have paired, lateral vaginae.  In more advanced mammals the reproductive tube fuses in the middle to form a single canal.

Opossum have a very short gestation period of just 12-13 days.  Each baby is about the size of a honey bee at birth.  The number of babies averages between 13-21 per litter but much larger litters are not uncommon.  Females usually have 13 mammae, not all of which may be functional.  Each embryonic baby must make its way from the vaginal opening to the pouch and attach itself to a nipple where it will complete its development for several more weeks.  The babies who are the first to attach themselves to working nipples survive, the rest will die and the mother will remove them from her pouch.

While the litter is attached to the nipples, females will lick the babies and clean the pouch.  But once they emerge from the pouch they must groom themselves.  Young begin to fend for themselves at about 3 months, emerging from the pouch and riding around on their mother’s back.  Males are not involved in rearing the babies at all, and not much maternal behavior has been observed in female opossum.  Once they get too big to ride on the mother’s back, it seems they are on their own and the litter generally disperses within one month of weaning.

Females can mate soon after the litter is weaned, thereby producing two litters in one season.  The young from the second litter are usually weaned and on their own by September or October but in some localities, late litter young may over-winter with their mother until the following spring.

Opossum have a high mortality rate; even the mortality rate of young in the pouch ranges from 10-25 percent.  Of those that survive until weaning, fewer than 10 percent live more than one year.


Opossum are omnivorous and eat anything that’s available.  They tend to eat more plants and worms in the spring, while eating insects, snails and amphibians in the summer.  They eat grains, fruits and nuts in the fall, and hunt small rodents like shrews, voles, rats and mice in the winter.  They are especially fond of persimmons and can often be found in the southern United States perched in a persimmon tree enjoying their favorite fruit.

Opossum also eat rattlesnakes, copperheads, and water moccasins and have apparent immunity to pit viper venom.  They love cat food which brings them into suburban areas, and they are known to kill rabbits and chickens and to take eggs and nestlings.

Opossum seem to prefer decomposing fruit or meat to fresh food.  One source notes that “carrion with maggots is a year-round treat” and that more opossum were caught using decomposed bait than fresh.[2]  Road kill makes up a favorite part of their diet.  This preference is often responsible for their demise as they can’t get out of the way of traffic quickly enough.  They have earned the nickname of “nature’s sanitation engineers” because they keep urban environments free of unwanted pests and dead animals.

They put on a thick layer of brown fat in late fall and early winter to help them get through the coldest months.  They can lose up to 45% of their body weight over the winter.  “Possum fat” is a well known folk remedy and is traditionally used as a base for herbal salves to alleviate inflammatory conditions like arthritis and rheumatism.

Unique Immune Features

Opossum are unusually resistant to many infectious diseases, including rabies (very unusual for a mammal).  This may be due to their relatively low body temperature of 94-97 degrees which makes it difficult for the rabies virus to survive.

As mentioned earlier, opossum have the ability to eat poisonous snakes and research suggests that their blood contains a factor that makes them immune to normal doses of pit viper venom.[3]  This Lethal Toxin Neutralizing Factor (LTNF) is being researched as a possible “universal” antidote for several animal, plant and bacterial toxins.

They are host to numerous parasites and diseases and can spread these to other animals (including humans).  In particular, they are the hosts of Sarcocystis Neuroma, a protozoan parasite that causes Equine Protozoal Myelitis, a serious, sometimes fatal, disease that affects the central nervous system of horses.


Important predators include great horned owls, dogs, and coyotes, and internal and external parasites (intestinal worms, fleas and ticks).

Their biggest predator of the opossum is man who may accidentally run them over or deliberately destroy them as “pests”.  Humans have traditionally hunted opossum as meat and trapped them for their fur.  In fact, they were introduced to the western United States as a source of food during the Great Depression.

Opossum also fall victim to malnutrition and starvation.

[1]  Web Article, “Order Didelphimorphia – American Opossums”, B. Pickett; http://www.bobpickett.org/order_didelphimorphia.htm, pg. 5 of 5.  Accessed 9/29/08

[2] Ibid.

[3] Ibid. (Proving continued below….)

The Proving

“The best opportunity for exercising our sense of observation and to perfect it, is by proving the medicines ourselves.” Samuel Hahnemann

On June 30th, 2008, fifteen brave provers were introduced to their supervisors at the NEW YORK SCHOOL OF HOMEOPATHY’S Hahnemannian proving of Didelphis Virginiana, the Virginia Opossum. It was decided that Day Zero, the day for taking the first dose of the remedy, would be September 2nd. Each prover met with his/her supervisor beforehand for an initial case taking and was instructed to speak with their supervisor on September 2nd before and after taking each dose of 30c. Provers were instructed to take no more than three doses a day for two days, however, if there was any reaction at all to the remedy, the provers were told not to repeat further doses.

Four provers needed only one dose in order to experience strong, recordable symptoms. Two provers took a second dose, two provers needed a third dose, and two provers took four doses. Five provers (four of them male) took all six doses with no effect. As usual, the master provers were concerned that there would either be no significant symptoms or too many symptoms, meaning that some provers would get quite sick. The fact is that with most provings, the truth lies somewhere in between. Three provers had very uncomfortable, strong symptoms, while four provers actually felt improvement in their overall states. Two of the Master Provers and four supervisors experienced strong emotional and signature symptoms.

It is important to remember that, as Hahnemann said, regardless of the symptoms that are produced during a proving, everyone involved is in a higher state of health or awareness after the experience. Not only have provers and supervisors helped to expand our materia medica, but everyone involved ends up in a healthier state as a result. The kind of introspection that provers are required to engage in during a proving is mind-expanding. Prospective provers, rather than feel as if they are about to become guinea pigs, should consider themselves more like Alice in Wonderland and feel confident that whether or not they suffer from temporary symptoms, the proving experience will enlighten them. A proving is a journey – an honorable journey for all involved. It should be embarked on with care and caution, but without fear. We hope to encourage many more Hahnemannian provings.

About the author

Susan Sonz

Susan Sonz

SUSAN SONZ, C.C.H., is the Director of the New York School of Homeopathy and principal instructor. She studied with many of the acknowledged masters in the field. Susan was awarded an H.M.C. (Homeopathic Master Clinician) diploma and is nationally certified (C.C.H.) by the Council on Homeopathic Certification. Susan publishes articles regularly for national journals, served for many years on the national board of the Council for Homeopathic Education (C.H.E.), and is the President of the New York State Homeopathic Association (NYSHA).
Susan's method of teaching includes the use of her own clinical case studies which serve to illuminate the remedy pictures, while reinforcing the homeopathic philosophy. She holds very high standards on homeopathic education, while imparting the information with humor and sensitivity. Susan lives and practices in New York City.


  • thank you for the guts to prove the opossum great vision i like that in homeopaths….keep up the good work thom sonnenberg dhm

  • Thank You Susan

    A new proving is always interesting,especially when one can have good and reliable notes about the origin of the proven material. This allows to understand the personnality of the remedy, and to compare it with the cured clinical cases.

    Therefore I find it very useful to find such work published freely in this Journal !
    Thanks once more
    Have a nice day

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