Adventures in the leech trade

I decided to say something about leeches while I was being given a biopsy in my neck, with an ultrasound-guided needle.  It's just one of those play-safe things: the cyst they were sampling is almost certainly benign, but it's atypical, so the medical consensus is that I should get rid of it,

A feeding leech on a human leg (see below for model credits).

I had a nurse and a doctor working on me, and we were chatting about phlebotomy (it always throws them a bit when the patient speaks the language) and weight loss.  

That was when I indicated that one of my temporary obsessions is the Australian leech export trade.  When I was driving home, it struck me that I ought to write these matters up here, because few people know much about them.

Before I get into that though, something that I only learned when I was writing Australian Backyard Naturalist: most leeches have three jaws and leave a Y-shaped incision.

The land leeches of Australia have just two jaws so they make a V-shaped incision. I had never realised that, even though, like anyone who has spent time in the Australian bush, I was familiar with them. Our land leeches don't show up in the arid zone, though the leech you see above came from a dry ridge on sandstone, during a dry spell in summer.

As early as 1817, explorer John Oxley knew all about leeches in the bush:

The leeches in the bushes were very troublesome, and made many plentiful meals at our expense: this would probably have done us no great harm, but the wounds which they made usually festered and became painful sores.—John Oxley, Journal of an Expedition in Australia, part II, 1817.

Around 1845, Ludwig Leichhardt had trouble as well, though his leeches were aquatic:

In the water-hole near our camp, there were numerous small brown leeches, which were very keen in the water, but dropped off as soon as we lifted our feet out of it. The hornets also were very troublesome…—Ludwig Leichhardt, Journal of an Overland Expedition in Australia: From Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845.

In 1849, on the ill-fated Kennedy expedition to Cape York in tropical Australia, botanist William Carron was troubled by leeches as well:

August 8…. We fortunately found water in a low place, and with difficulty lighted a fire, everything being saturated with rain. We then laid down and endeavoured to sleep, but were unable to do so from the number of small leeches which attacked us. I was obliged to get up several times in the night, and in the morning I found myself covered with blood.—William Carron, Narrative of an Expedition Undertaken Under the Direction of the Late Mr. Assistant Surveyor E. B. Kennedy (1849)

Leeches are attracted by body heat, they say. This one is questing for prey.

You can use their heat sense to attract leeches into a jar like this. The hand is that
of my wife, Chris, who is a leech magnet, but quite calm about it. The first shot is
of her leg: when she found the leech, she called me to get the camera so I could
record it before she removed the attacker.

Not everybody saw the leech as a threat. On March 16, 1844, the Westminster Hospital in London advertised in The Times for  PROPOSALS for SUPPLYING a range of items for six months from March 31, including butcher's meat, bread and flour, butter, cheese and lard, London porter, linen, drapery, oatmeal, linseed and barley, tea, sugar, and rice, potatoes, oilman's goods, milk, printing, leeches, and lint.   (The Times, Wednesday, Mar 20, 1844; pg. 3; Issue 18562; col A)

The very next year, Australians started exporting leeches:

Exports per Emma Sherratt for the Mauritius. 6 cows, 6 horses, 100 sheep, 40 tons dried fish, several tons of potatoes, 5 casks grapes, 6 jars of leeches, with various other articles of colonial produce.The Perth Gazette and Western Australian Journal,  Saturday 22February 1845, page 2 

After a rather tiresome exploratory voyage to the unknown markets of the Mauritius, the supercargo of the Emma Sherratt offered this report (in part):

Leeches.—Pondicherry furnishes the Mauritius abundantly with leeches. They sell from 10 doll, to 20 doll, per hundred, and sometimes as high as 30 doll, per dozen. They arc brought in earthenware pots, half filled with earth, which is constantly moistened with fresh water, the earth sometimes completely changed.The Perth Gazette and Western Australian Journal, Saturday 5 July 1845, page 2

But there was dirty work afoot, with French leeches being artificially enlarged in the interests of profit.  M. Chevalier, Professor of the School of Pharmacy and a member of the Academy of Medicine, reported the Maitland Mercury and Hunter River General Advertiser, had published a pamphlet exposing the wicked practice of feeding some of the 500,000,000 leeches imported into France each year on domestic stock.

The leeches were sold by weight, and where 2000 middle-sized leeches might weigh two and a half pounds, once they were gorged, the leeches would weigh four and a half pounds, raising their value from 75 francs to 180 or 200 francs. Interestingly, given the date, well before the germ theory was accepted, the main concern of Chevalier and other eminent medical authorities was that:

…the origin of the blood contained in the bodies of the gorged leeches being unknown, may become the source of contagious diseases transmitted from animals to man … an imposition alike injurious to commerce and to health.The Maitland Mercury, and Hunter River GeneralAdvertiser, Saturday 20 June1846, 3.

SPECIAL NOTE:  For all Scientific American pieces that I cite in the rest of this entry, you go to the Scientific American archive http://digital.library.cornell.edu/s/scia/index.html and burrow down.  Each citation has date, volume and page number, and you can use those to get to the page.

The 19th century offered a wealth of information for leech lovers, For example:

How to make Leeches Bite. Dr. Rennes, of Bergerac, advises that the leeches should be put for an instant into weak wine-and-water, the better for being a little warm, just before applying them ; no sooner are they laid on the part than even the most sluggish pierce the skin instantly ; those even that had been for a short time before used, immediately attach themselves. In the Hotel Dieu, the practice is to wring a linen cloth out of undiluted wine, and wrap the leeches in it for a few moments, which is found to have the desired effect.

Scientific American 21/10/1848, 40 vol 4

 But why would you want a leech to bite?  To cure the patient, of course! And aside from general maladies, leeches were set specific targets:

Leeches recommended on the temples when cholera affected the head.  "Should the head be affected and the face flushed, cold lotions should be applied and leeches to the temples."

Scientific American 30/12/1848, 115

In 1863, Scientific American recommended leeches to treat people poisoned with cantharides or Spanish Fly.  (Scientific American 5/9/1863, 151.)

A writer called F. Lancelott, in Australia As It Is, vol. I, p. 49, claimed that Murray shepherds persuaded Aborigines to wade in the waters and allow leeches to attach, then come out of the water so the leeches could be harvested. The leeches were sold to "the faculty in the colonies".

This is not mentioned elsewhere, and somebody was probably pulling Lancelott's leg.  There was certainly an industry using fresh animal skins to lure and hold leeches.  Susan Priestley, in Echuca, p. 46, says that the leeches were caught, stripped of slime and packed in blue clay, to be shipped to London where they sold for £4/10/- or £5 per thousand, "as they were much in demand by medical men".

By 1862, leeches typically brought between £1/10/- and £5 a thousand. My source here is a slightly distant one: the Sydney Morning Herald, 4/8/1862, quoting the Pastoral Times of July 26 and quoted by G M Hibbins, Barmah Chronicles, p. 118. (I have yet to find the original, but this story gives the bloody-hide method.)

They were caught by laying out blood-smeared hides overnight, and in the morning, the thousands of leeches were stripped off, 'squeezed' to remove the slime and then put in blue clay in a box. If they were not cleaned of the slime, they would surely die.

The trade was even noted in the USA.

A very remunerative business has lately grown … Melbourne in the exportation of leeches. The trade is principally carried on In connection with the operations of the Murray River Fishing company, the fishermen there employed turning their attention at seasons unfavorable to the fishery to the collection of leeches. From 150,000 to 210,000 leeches are sometimes collected in one of the trips of the company’s steamers. They are then packed and conveyed to Melbourne, where a large proportion of them are put up for transmission abroad, great numbers being sent to London and Paris, where it is stated they are preferred to leeches brought from any other place.Scientific American 3/8/1867, 102.

The trade must have reached a peak in the 1860s, going on this report:

SOME articles intended to be transmitted In the English mails, but which were not forwarded by the officials, are thus described by a cotemporary :—Two canaries, a pork pie from Devonport to London, pair of white mice, leeches in bladder, bottle of cream, sample of cider, a roast duck, a loaded pistol, fish, reptiles, &c.Scientific American 19/12/1863, 387

Perhaps the postal authorities were worried that somebody might swallow the leeches: it was known to happen when drinking leech-infested water.

Accidents from swallowing leeches.  It appears from an article in the Archives Générales de Médecine, that the soldiers in Algeria are particularly liable to accidents of this description. At the time when the leeches are swallowed, they are so small as readily to escape detection ; they are filiform, and rather resemble a blade of grass than anything else. They usually become attached to the isthmus faucium, or to the pharynx, and are sometimes found in the nostrils. When once they have become fixed, they generally remain for a considerable period, and undergo their development rapidly. Dr. Baizeau records a case in which they remained for more than six months within the pharynx. They very seldom come away of their own accord, and must usually be extracted forcibly.

If they are too deeply seated to be caught by a forceps, then the patient must gargle his throat with a mixture of vinegar, water, and common salt, and must continue the process for several days. But even this sometimes proves unavailing. The symptoms are those of irritation in the part, together with occasional hemorrhage. The latter is often mistaken for a symptom of disease of the lungs, stomach, &c. The only preventive appears to be a caution to the soldiers not to drink water from streams, &c., when they are on the march. It is a remarkable circumstance that a leech can live so long a period under conditions so opposite to those it previously enjoyed, and bears out In some measure the views of those who class the Hirundinei with the Trematoda and Planaria.

Scientific American 20/2/1864, 122

The Tempest Prognosticator

Somewhere I have a note about a device of this sort being displayed  at the Great Exhibition in 1851, well before the 1854 report below.  If my memory is right, it was dismissed even in 1851 as not all that new!  There may also have been something in an earlier Scientific American, but it isn't where I expected it. If you enter Tempest Prognosticator into your search engine, you will find a great deal more information.

Here, for what it is worth, is what Scientific American had to say about it:

A correspondent of the “Philadelphia North American” gives an interesting description of an ingenious instrument, contrived by Dr. Merryweather of Yorkshire, Eng., the great working principle of which is founded on the sensitiveness of leeches to the changes of the weather. It is well known that leeches confined in a bottle partly filled with water, are accustomed, previous to a storm, to rouse from their sluggishness and exhibit signs of extraordinary perturbation. They will swim in all directions, and rising one after another to the top of the water, commence climbing the side of the bottle.

Availing himself of this time-honored custom among leeches, Dr. Merryweather arranged a number of bottles on a stand, each containing a leech and a metallic tube of a particular form, covered with shellac varnish, so that no metal could come in contact with the animal.— When a change in the weather was about to take place, the leeches would crawl into this metallic tube, and in so doing displace a small piece of whalebone which was arranged so as to partially close the opening. To this whalebone was attached a wire, which, passing upward through the mouth of the bottle, connected with the hammer of a bell, so that whenever the leeches were influenced by the electro-magnetic state of the atmosphere to ascend the tube, notice of the fact would be promptly transmitted to the ears of their master.

But it is not absolutely necessary that every one should have such a finished apparatus as that of Dr. Merryweather. On board of vessels it would only be necessary to keep a few leeches in a bottle, placed in some prominent place where the lookout could occasionally examine their movements, and the necessary warning be conveyed in ample time.

Dr. Merryweather seems to have tested his invention fairly. For an entire year (1850) he wrote to the president of the Philosophical Society of Whitby, accounts of the storm indications of his leeches; and in no instance did they prove incorrect. If these results are verified by other observations, a leech barometer may be deemed an indispensable appendage to every ship and every household.
Scientific American 11/3/1854, 208.

Leeches get along like looper caterpillars ("inch worms"), and make a
fascinating study, but trying to photograph a time series is a real pain.

 Finally, here is a link for extra reading on leeches from the Australian Museum.