LEECH 405
lateral cæca of the stomach, but with two long posterior cæca, is abundant in British ponds and lakes, as also is Nephelis vulgaris, L. (fig. 7), a species about 3 inches in length. Its dorsum is brownish-yellow, often with a conspicuously tesselated appearance, while the under surface is pale olive. The eyes are eight – four being placed somewhat in a semicircle, and four a short distance behind, wider apart, and at a different angle. It is active and rest less, keeping up an undulating motion of its body when attached by the posterior sucker, apparently as in the Phyllodocidæ, to promote respiration. It also swims on edge through the water like an eel. The skin is exceedingly sensitive to the vapour of chloroform, while the contact of a single drop causes tetanic convulsions, and the annelid dies, quite rigid. The digestive canal is nearly simple, and there are no buccal teeth. The dorsal blood-vessel is absent. The ova are deposited in a horny capsule fixed horizontally to sub-aquatic structures, and it is curious that Linnæus described it as a hemipterous insect under the name of Coccus aquaticus. On Bergmann's paper in which the error was corrected the great Swede wrote "Vidi et obstupui." Nephelis feeds on earthworms, larvæ, mollusks, and other organisms. Trochcta subviridis, Dutrochet, is a large European form (7 inches in length), which frequents the marshes and ditches of France and Algeria (and also rarely, apparently from introduction, of England). It leaves the water to follow the earthworms on which it feeds. There are no buccal teeth, and the alimentary tube is only slightly camerated. In Ceylon the Hirudo tagalla or ceylanica, a land-leech about an inch in length, is a great annoyance to travellers, especially in the rainy season, attacking men and horses when journeying through the woods and jungles, and causing considerable irritation from its bites. They come in troops out of the grass and dead leaves, and one cannot leave the gravel in the gardens in some places without being attacked. Leech-gaiters, therefore, are worn by many residents for protection. A similar form occurs at an elevation of 4000 feet in the Philippines, and others in Java and Sumatra; and Sir Joseph Hooker found them at a height of 11,000 feet on the Himalayas. Land-leeches also exist in Australia, Japan, and Chili, – where very few occur in the water. They frequent plants, trunks of trees, and shrubs, as well as grass. An eyeless leech, called Typhlobdella, in habits the subterranean waters of the Baradla cave in Hungary. An allied eyeless form, Cyliobdella lumbricoides, Grube, which was found by Fritz Muller in Brazil, lives in damp earth. It has a slender spindle-shaped outline. The exact position of the gigantic Macrobdella valdiviana of Filippi, a South American leech measuring about 2½ feet, is uncertain. It is eyeless, and has neither lips nor teeth. It probably lives in damp earth, and feeds on earth worms.
Fig. 7 – Nephelis vulgaris, L. Dorsal view. Slightly enlarged.
In the third family, Branchiobdellidæ, the irregularly annulated body is elongated, somewhat cylindrical, with a bilobed eyeless snout, and a sucker at the posterior end. There is no proboscis, but the pharynx has two flattened edentate pads (dorsal and ventral). The body is provided with a cœlom or body-cavity, an unusual feature in the leeches. The alimentary canal is simple. There are only two longitudinal vascular trunks – a dorsal and a ventral, the former showing a dilatation behind the cephalic branches, sometimes termed a heart. Two pairs of segmental organs are present, the posterior pair of which are modified for the conveyance of the ovarian products to the exterior; for the ovaries, which are situated far back, discharge their contents into the body-cavity. The best known are Branchiobdella astaci, Odier,and B. parasita, Henle, which occur as ectoparasites – the former (smaller) on the branchiæ, the latter under the tail and on the antennæ and eyes, of the crayfish. Myzobdella, Leidy, and Temnocephala, Gay, are allied forms. The latter is a curious Chilian leech having five digitate processes attached to its anterior end, behind which a pair of eyes and the mouth are situated. A sucker exists posteriorly. In the same family are placed the aberrant types Acanthobdella and Histriobdella. The former is characterized by a somewhat flattened spindle-shaped body resembling a Gephyrean, bluntly pointed in front, furnished with minute hooks near the anterior end, and a posterior sucker. The A. paledina, Grube, a fish-parasite from Sicily, is an example. The latter (Histriobdellidæ} are remarkable in the group in being diœcious instead of hermaphrodite, and somewhat resemble in outline grotesque insect-larvæ. The peculiar beak-like head fitted for suction, the jointed body, and the pair of posterior suckers are characteristic. They are ectoparasites on marine Crustacea; thus Histriobdella homari, Van Beneden, occurs on the lobster, and Saccobdella on other decapods.
Formerly Udonella and Entoldella were included under the leeches, but they seem to be more correctly located amongst the Trematoda. Until lately Malacobdella was also considered one of the group, but its ciliated skin, separate nerve-cords, proboscis, and development point it out as an intermediate type allied to the Nemerteans.
The following works amongst others may be referred to for more detailed
accounts of the order: – Noble, On the Medicinal Leech, 1822; Rawlins Johnson On the Medicinal Leech, 1825; Brandt and Ratzeburg, Medicinische Zoologie, 1829; Moquin-Tandon, Monographie de la Fam. des Hirudinées, 2d ed., Paris 1846; R. Leuckart, Parasiten des Menschen, vol. i., 1863; Sir J. G. Dalzell. Powers of the Creator, vol. ii., 1853; G. Johnston, Catalogue of Worms, British Museum, 1865. Also the various memoirs of Carena, M. Thomas, Delle Chiaje, Gratiolet, H. Rathke, Van Beneden, F. Leydig, E. Grube, Kinberg, Robin, Vaillant, Dorner, Kennel, Schneider, Hoffmann, Hermann, Whitman, Bourne, Ray Lankester, and Ranke. (W. C. M.)
LEECH, John (1817-1864), the most genial of the humorous draftsmen of our century, was born in London on the 29th of August 1817. His father, a native of Ireland, was the landlord of the London Coffee House on Ludgate Hill, "a man," on the testimony of those who knew him, "of fine culture, a profound Shakespearian, and a thorough gentleman." His mother was descended from the family of the famous Richard Bentley. It was from his father that Leech inherited his skill with the pencil, which he began to use at a very early age. When he was only three, he was discovered by Flaxman, who had called on his parents, seated on his mother's knee, drawing with much gravity. The sculptor pronounced his sketch to be wonderful, adding, "Do not let him be cramped with lessons in drawing let his genius follow its own bent; he will astonish the world," – an advice which was strictly followed. One of his early productions, a mail-coach, done when he was six: years old, is already full of surprising vigour and variety in its galloping horses. Leech was educated at Charterhouse, where Thackeray, his lifelong friend, was his schoolfellow, and at the age of sixteen he began to study for the medical profession under Mr Stanley at St Bartholomew's Hospital, where he won praise for the accuracy and beauty of his anatomical drawings. He was then placed under a Mr Whittle, an eccentric practitioner, the original of "Rawkins" in Albert Smith's Adventures of Mr Ledlury, and afterwards under Dr John Cockle; but gradually the true bent of the youth's mind asserted itself, and he drifted into the artistic profession. He was eighteen when his first designs were published, a quarto of four pages, entitled Etchings and Sketchings by A. Pen, Esq., comic character studies from the London streets. Then he drew some political lithographs, did rough sketches for Bell's Life, produced an exceedingly popular parody on Mulready's postal envelope, and, on the death of Seymour, applied unsuccessfully to illustrate the Pickwick Papers. In 1840 Leech began his contributions to the magazines with a series of etchings in Bentley's Miscellany, where Cruikshank had published his splendid plates to Jack Sheppard and Oliver Twist, and was illustrating Guy Fawkes in sadly feebler fashion. In company with the elder master Leech designed for the Ingoldsby Legends and Stanley Thorn, and till 1847 produced many independent series of etchings. These, however, cannot be ranked with his best work; their technique is exceedingly imperfect; they are rudely bitten, with the light and shade out of relation; and we never feel that they express the artist's individuality, the Richard Savage plates, for instance, being strongly reminiscent of Cruikshank, and "The Dance at Stamford Hall" of Hablot Browne. In 1845 Leech illustrated St Giles and St James in Douglas Jerrold's newly started Shilling Magazine, with plates more vigorous
