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The Proving Of Didelphis Virginiana – The Virginia Opossum

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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.


In a proving, signature symptoms are fascinating. They seem especially significant now considering Rajan Sankaran’s work with the Sensation System of homeopathy. The signature symptoms of homeopathic remedies are reported by provers in an uncompensated manner, and they serve as confirmatory evidence that our understanding of the remedy begins with the substance itself. These signature symptoms, which reflect the nature of the substance, deepen our understanding of similitude. These are some of the more significant substance/source related reports, with notations reproduced from the Natural History section.

Dream – While I’m in the shower this morning, I remember something about a dream in which I was talking about the importance of washing one’s feet! Prover #3, Day 01

Note: Opossum prefer low, damp woodlands near permanent bodies of water such as lakes, ponds, streams or rivers.  They are known to be strong swimmers…As they roam their territory, they tend to follow water courses…Opossum wash their faces with their front paws like a cat does.  They also use their hind “thumb” as a handy grooming aid.

Dreamed about a bunch of houseflies on a white background, then I woke up in a sweat and felt very hot. Prover #10, Day 01

Dreamed of a bunch of houseflies buzzing around in the corner of my kitchen.  I felt hot again and woke up. Prover #10, Day 01

7:30 am – I put my son on the bus for school and noticed that my dogwood tree was buzzing loudly.  I took a closer look and the tree’s leaves were covered by houseflies!  Never saw anything like it before – there were at least 100 flies on the tree! Prover #10, Day 02

9:30 am – I went to put something into my car and there are a bunch of flies in the car – maybe 5 flies.  Prover #10, Day 02

7:00 pm – I was in Manhattan having dinner with a bunch of people and we order a bottle of wine.  When the wine glasses are brought out, mine had a dead fly in it.  The waiter took it away and brought me a clean glass. Prover #10, Day 06

I’m experiencing intermittent wafting of the odor of a dead animal.  It’s a very distinct odor of either a dead animal or the smelly juice that drips from a garbage truck.  Prover #10, Day 02

Note: Opossum seem to prefer decomposing fruit or meat to fresh food.  Carrion with maggots is a year-round treat and more opossum are trapped by using decomposed bait than fresh.  Road kill makes up a favorite part of their diet.

Dream – My mother’s freezer was really dirty with old food and spilled chocolate ice cream, so I cleaned it. Unusual. Prover #10, Day 01

9:30 am -12:30 pm.  It was my first day volunteering to do work at an organic co-op that I recently joined.  My job was to sort through the fruit, removing the molded, rancid pieces for the compost pile.  Being a newbie at the co-op, they also gave me a really dirty refrigerator to clean. Remember my dream about the dirty refrigerator?   Prover #10, Day 15

Note: They have earned the nickname of “nature’s sanitation engineers” because they keep urban environments free of unwanted pests and dead animals.

It’s toward the end of the proving and I’m realizing that I’ve been eating a lot more fruit than usual. I usually eat raw vegetables, but since taking the remedy, I’ve been buying extra amounts of fruit and eating it daily: pineapple, papaya, bananas, blueberries, blackberries, raspberries, apples. Prover #10, Day 11

Note: Opossum are omnivorous and eat anything that’s available.  They eat grains, fruits and nuts in the fall. They are especially fond of persimmons and can often be found perched in a persimmon tree enjoying their favorite fruit.

Dream: There was a raccoon under my son’s sheets. He was asleep. The raccoon slithered out and it had the face of a possum! Prover # 14, Day 22

Note: This dream was reported to the supervisor prior to the extraction meeting, before the prover knew the source of the remedy. It’s significant in that raccoons and opossum not only share the same habitat, but have been known to share dens during the cold of winter.

Master Prover, Susan Sonz, was at a friend’s home in Sag Harbor on Day 1 of the proving. That night, a large female opossum came to the back door and stayed for over an hour. Susan’s friend had never seen an opossum before, although she has lived in that area for the past ten years.


Several strong themes emerged at the extraction meeting on September 28, 2008. Prover #1, who was the first to report, began by describing a panic attack that had occurred the day before at a child’s birthday party. Her description reminded the master provers of the coma-like state (“playing possum”) of a terrified opossum.

There were many reports of hypersensitivity to smells and sounds with conflicting reports of detached feelings.

Many provers complained of symptoms that involved mind confusion, memory problems, and spaciness.

Water was discussed; there were dreams of water and floods, sensations of clogged ears, and actual plumbing problems.

And, to be expected, symptoms around the themes of children and protection were discussed. In fact, two women who had stopped nursing months before, started lactating again spontaneously.

Here are the major themes and words of the provers:

1. OUT OF CONTROL vs. CALM (the opossum is often described as placid).

The first five comments were reported by Prover #1 at the extraction meeting:

I walk into some over-stimulating situation (auditory or visual or whatever) and the first thing that happens is I notice I don’t know where to look – can’t keep my eyes fixed in any one place for any particular time.

I feel a heat rush – particularly on my forehead and face; like a hot flush; face feels like it’s burning, my hands feel numb, I have a tight squeezing sensation around my ribcage; can’t get a breath; I feel like my heart is racing and pounding; feel giddy and ridiculous.

Depending on the situation, maybe embarrassed – feel like I’m not handling myself well; feel like I’m babbling and, I’m not particularly shy so I don’t normally feel embarrassed by acting like a jackass – felt dumb; laughing; making a fool of myself; like I can’t handle things.

At a playground with my kids – they were doing construction and there were a billion kids around.  I couldn’t keep track of my kids; couldn’t see them.  I gotta get out of here – just can’t do it.  Went home and the whole way home I was just giggling to myself – felt a rush.  There are circumstances where I really just can’t function.

I couldn’t write – had a really hard time and I’m someone who writes a lot.  I generally spend a couple of hours a day writing.  It’s what I do.  I hadn’t been able to – couldn’t answer my mom’s email. Prover #1, Extraction Meeting

[6 min. after Rx] I feel like the remedy is “hitting” me now.  I feel shaky and a little out of control.  It feels difficult to write.  Prover #1, Day 00

[2 min. later]  I feel myself sitting really still.  Eyes looking around calmly, emotionlessly.  Feel very still.  Legs feel still with no desire to move.  Not sleepy or lethargic, just still.  Prover #1, Day 00

My husband and son tell me that I seemed happier and more easy going the past two days. My son says I seemed like I was taking “happy pills” on Friday. [Day 00] I realize I was not bothered by little things that usually annoy me, like messiness in my house (e.g., piles of newspapers everywhere). This morning I’m more irritable about messiness again. Prover #3, Day 02

I think my mood is still a little calmer than usual for me. Annoying little things like waiting in line or waiting for the very slow elevator in my office building aren’t bothering me quite so much. I’m letting the annoyance kind of float away – or maybe it’s me who’s floating through my life a little bit more than usual. My mood is cheerier and I like being this way. Prover #3, Day 03

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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