Dropsy, Digitalis and Darwin (Erasmus, that is)

So. It's National Poetry Month. Type that key phrase into the "search" query field on the main page of SB, and you'll find that April brings forth a veritable poetry slam among Science Bloggers. In this fine tradition, I will don my black trousers, turtleneck, jaunty (but dirty) beret, take a drag from my half-smoked Gauloise ciggie and go Boho here with a selection from the original Botanical Pornographer, Erasmus Darwin, Charles' grandfather. Today, I have chosen his ode to digitalis. Cue bongo drums.

Bolster'd with down, amid a thousand wants,

Pale Dropsy rears his bloated form, and pants;

"Quench me, ye cool pellucid rills!" he cries,

Wets his parch'd tongue, and rolls his hollow eyes.

So bends tormented TANTALUS to drink,

While from his lips the refluent waters shrink;

Again the rising stream his bosom laves,

And Thirst consumes him 'mid circumfluent waves.

--Divine HYGEIA, from the bending sky

Descending, listens to his piercing cry;

Assumes bright DIGITALIS' dress and air,

Her ruby cheek, white neck, and raven hair;

Four youths protect her from the circling throng,

And like the Nymph the Goddess steps along. -

-- O'er Him She waves her serpent-wreathed wand,

Cheers with her voice, and raises with her hand,

Warms with rekindling bloom his visage wan,

And charms the shapeless monster into man.

Dr. Darwin's notes on foxglove and digitalis as treatment for dropsy follow:

[Digitalis. 1. 425. Of the class Two Powers. Four males, one female, Foxglove. The effect of this plant in that kind of Dropsy, which is termed anasarca, where the legs and thighs are much swelled, attended with great difficulty of breathing, is truly astonishing. In the ascites accompanied with anasarca of people past the meridian of life it will also sometimes succeed. The method of administering it requires some caution, as it is liable, in greater doses, to induce very violent and debilitating sickness, which continues one of two days, during which time the dropsical collection however disappears. One large spoonful, or half an ounce, of the following decoction, given twice a day, will generally succeed in a few days. But in more robust people, one large spoonful every two hours, until four spoonfuls are taken, or till sickness occurs, will evacuate the dropsical swellings with greater certainty, but is liable to operate more violently. Boil four ounces of the fresh leaves of purple Foxglove (which leaves may be had at all seasons of the year) from two pints of water to twelve ounces; add to the strained liquor, while yet warm, three ounces of rectified spirit of wine. A theory of the effects of this medicine, with many successful cases, may be seen in a pamphlet, called, "Experiments on Mucilaginous and Purulent Matter," published by Dr. Darwin in 1780. Sold by Cadell, London.]

So let's parse this baby!

Dropsy is an archaic term for edema, that is, the swelling of soft tissues due to the accumulation of excess water. Why Dr. Erasmus chose to equate Dropsy with Tantalus, I'm not sure, but Hygeia's (Hygieia - goddess of health) personification as Digitalis makes sense. She was one of the six daughters of Asclepius. Like her father, Hygieia is associated with snakes, hence "serpent-wreathed wand," the symbol of medicine. The Bowl of Hygieia...

...is a symbol of pharmacy.

Foxglove contains digoxin, a cardiac glycoside that inhibits membrane-bound Na+/K+ - ATPase, thus affecting intracellular potassium and calcium levels.

This in turn acts to increase the strength of the heart muscle's contractions. A patient with "dropsy" due to congestive heart failure would be likely to respond well to a digitalis concoction described in such loving detail by Dr. Erasmus. Digoxin, marketed as Lanoxin continues to be an important pharmaceutical treatment for congestive heart failure. However, digoxin has a very narrow therapeutic window, that is, the dose that provides efficacy is very close to that which will cause severe adverse effects, cf. Darwin's description of "very violent and debilitating sickness." Dosage was dicey, too, in Dr. Erasmus' time. One couldn't know exactly how much active principles the foxglove plants contained. Darwin's notes indicate that patients were basically titrated with the elixir in an attempt to effect efficacy at the verge of toxicity. This is not an uncommon feature of such natural products: they can be very dirty drugs.

On the botanical side of things, Darwin poetically describes a couple of key taxonomic facts about Digitalis purpurea. The "Four youths" around Hygieia as Digitalis represent the four stamens (male bits) of the flower; the lone goddess/nymph represents the one pistil (female floral part). "Class Two Powers" means that two of the four stamens are taller than the others. The "ruby cheek, white neck and raven hair" would seem to allude to the coloration of the tubular foxglove flower.

Granted, Erasmus' poetry is turgid and overblown, but his joy of science infuses his verses. And as a former botany major as an undergrad, I find them pretty entertaining. I'll inflict the meager audience of the Chimp Refuge with a few more of these during the month of April.

Ref: The Botanic Garden. Part II. Containing the Loves of the Plants. Erasmus Darwin. The Echo Library, Teddington, Middlesex UK. 2007. 56-57.