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. |