70 NATURAL HISTORY OF BRITISH FRESH-WATER LEECHES.
Since observing this, I find that a Russian naturalist, Moltschanov
(36), noted that when the young of Hemiclepsis marginata were 
taken from their parents, they crept about until they met with
some other leech (not necessarily of the same species) to which
they attached themselves. I have failed to observe any evidence
of the maternal and filial instincts in species which deposit their
eggs in cocoons, which are left to their fate, receiving no further
attention from the parent.
Economic uses, &c.—The only British leech which is of any
economic importance is the Medicinal Leech (Hirudo medicinalis).
It is seldom used now, but was a favourite agent for blood
letting during the first half of the nineteenth century. Leuckart
(35) states that in 1863 seven million leeches were used in London
alone, and France consumed between twenty and thirty millions
in 1846.
Leech-gathering was at one time a fairly common pursuit
in this country. It was carried on by the poor, especially
old people, women and children. Dalyell (12) remarks that
"a lady in the county of Fife is the reputed owner of a pond
containing Medicinal Leeches, which she reserves exclusively
for the poor." Johnston (32) (p. 310) says that an old woman
(Mrs. Darling) used to collect Medicinal Leeches in a small
lakelet at Whitehall, near Chirnside—this was from 1808-1825.
Wordsworth, in his poem Resolution and Independence, writ-
ten about 1807, describes the leech gatherer as a very old man.
" He told that to these waters he had come
To gather leeches, being old and poor:
Employment hazardous and wearisome!
And he had many hardships to endure;
From pond to pond he roamed, from moor to moor."
Medicinal Leeches were evidently becoming scarce at this
period, for the poem continues:—
" He with a smile did then his words repeat;
And said, that, gathering leeches far and wide
He travelled ; stirring thus about his feet
The waters of the pool where they abide.
'Once I could meet with them on every side;
But they have dwindled long by slow decay;
Yet still I persevere, and find them where I may.'"
The extensive use of Medicinal Leeches at the beginning of the
19th century resulted in the formation of a thriving industry
all over Europe.