In the adult state the female Echinorhynchus gigas is a huge species, occasionally reaching two feet in length, with a breadth of one third of an inch. The male rarely exceeds three inches. This worm is common in swine, both wild and domesticated. According to Schneider the embryos take up their residence in the grubs or larvæ of the cockchafer (Melolontha vulgaris), a discovery which very readily explains the manner in which hogs become infested. Whether E. gigas be a human parasite or not, it is certainly very injurious, not to say destructive, to swine. Although this parasite must be quite common in England I have experienced great difficulty in procuring specimens. In the second book of this work I shall give some interesting particulars furnished by the memoir of Prof. Verrill and privately by Mr George Wilkins. (See ‘[Parasites of the Pachydermata]’.)
Bibliography (No. 35).—Blanchard, in ‘Cuvier’s Règne Animal,’ tab. 35 (good fig.), and in ‘Ann. d. Sci. Nat.,’ ser. xii.—Bremser, ‘Icones,’ tab. vi.—Cobbold, “Parasites of the Hog,” the ‘Veterinarian,’ 1875.—Idem, ‘Manual,’ l. c., p. 123.—Davaine, l. c., ‘Syn.,’ p. 83.—Diesing, l. c., ii, p. 2.—Dujardin, l. c., p. 503.—Goeze, l. c., s. 143 (good figs.).—Gurlt, l. c., s. 367.—Heller, ‘Darmschmarotzer,’ l. c., s. 663.—Lambl, l. c., supra, Feb., 1859.—Leuckart, l. c., Bd. ii, s. 729; also in ‘Bibl. Univ.’ for March, 1863, and in ‘Ann. Nat. Hist.,’ vol. xii, 1863.—Owen, l. c., in ‘Todd’s Cyclop.’ (figs. after Cloquet).—Rudolphi, ‘Synops.,’ pp. 63 and 310.—Schneider, in ‘Arch. f. Anat. und Phys.,’ 1868.—Idem, in ‘Sitzungsb. der Oberhess. Gesellsch. f. Nat.,’ &c., 1874 (quoted by Leuckart); see also ‘Ann. Nat. Hist.,’ 4th series, vol. vii, p. 441, 1871.—Verrill, ‘The external and internal Parasites,’ &c., l. c., p. 109.—Welch, “The presence of an Encysted Echinorhynchus in Man,” ‘Lancet,’ Nov. 16, p. 703, 1872.—Westrumb, ‘De Helm. Acanth.’ (good figs.), 1821.
SECTION IV.—Part II.—Suctoria (Leeches)
As explained in the Introduction we must regard the Leeches and many allied forms of Suctorial Annelids as creatures possessed of semi-parasitic habits. They are, perhaps, something more than what Van Beneden styles “free parasites”—an expression which almost looks like a contradiction of terms. I cannot here, however, stop to discuss questions which lie, as it were, on the border-land of parasitology. Three species of leech are more or less commonly employed in medicine. These are the grey leech (Sanguisuga medicinalis, Savigny), the green-leech (S. officinalis, Sav.), and the dragon-leech (S. interrupta, Moq.-Tandon). The two former abound in Central and Southern Europe, being also present in North Africa, the last named inhabiting Barbary and Algeria. So abundant are leeches in the country bordering the Mediterranean that during the invasion of Egypt by Napoleon the French soldiers suffered seriously from their attacks. When the men lay down to drink, the leeches (Hæmopis sanguisorba, Sav.) affixed themselves to their mouths and nostrils, producing serious distress. They also attacked horses, camels, and cattle. In like manner the Ceylon and Philippine Island leeches (S. ceylonica, Moq.-Tand., or S. tagalla, Meyen), of which there are several varieties, prove exceedingly troublesome to Europeans. These leeches, not being aquatic forms, occupy woods and damp places. Unless the limbs of travellers are well protected, the presence of the blood-suckers is soon discovered by the trickling of blood from the limbs and lower part of the body. The leeches even sometimes creep up to the neck and other adjacent parts. These “free parasites” also attack horses, causing much loss of blood. Terrestrial leeches abound more or less in all warm countries. Sir J. Hooker encountered them in the Himalayas, and they are common in China, Japan, Java (S. Javonica, Wahlberg), and other eastern parts. They likewise abound in Brazil and Chili. The American leeches for the most part belong to the genus Hæmenteria (H. Mexicana, H. officinalis, and H. Ghiliani, Filippi). The last named is common in Brazil, the other two being Mexican forms. Another species, which is blind, has been found in Brazil by F. Müller (Cyclobdella lumbricoides). Not only the above-named species, but also many other kinds of leeches are in the habit of attacking man and the domestic animals, but the subject is too extended and special to be fully dealt with in this work. Almost a legion of species are known as externally parasitic upon Fishes, Chelonian and Batrachian reptiles, Crustaceans, and Echinoderms.
Bibliography (No. 36).—Blainville, ‘Dict. des Sci. Nat.,’ tom. xlvii, p. 257.—Brandt (und Ratzeburg), ‘Medicin. Zoologie,’ Bd. ii.—Brightwell, ‘Ann. and Mag. Nat. Hist.,’ ix, 1842.—Diesing, ‘Syst.,’ vol. i, p. 465, and “Revis. der Myzelminth. (Abth. Bdellideen),” in ‘Sitzungsb. der math.-nat. Cl. d. k. Akad. der Wissensch.,’ Bd. xxxiii, s. 473.—Ebrard, ‘Compt. Rend.,’ 1856, p. 1012.—Idem, ‘Monogr. des sangues Méd.,’ 1857.—Filippi, De, ‘Mem. Accad., &c., Torino,’ and in ‘S. und K. Zeitsch.,’ 1829.—Idem, “Nuovo genere,” &c., in ‘Gaz. Med. Lombard,’ 1849.—Grube, ‘Fam. d. Annelid.,’ s. 109.—Hofmeister, in ‘Burmeister’s Zeitung für Zool.,’ 1848.—Johnson, ‘Treatise on the Medicinal Leech.’—Leuckart, l. c., Bd. ii, s. 634–739 (with many refs.)—Leydig (“Anat.”), ‘S. und K. Zeitsch.,’ Bd. i.—Moquin-Tandon, ‘Monogr. de la fam. des Hirudinées,’ 1846.—Idem, in his ‘Medical Zoology’ (Hulme’s edit.), 1861, p. 137.—Müller, F., in ‘Archiv f. Naturg.,’ 1846.—Pereira, in his ‘Materia Med.,’ vol. ii, p. 2197, 1853.—Savigny, ‘Descript. de l’Egypte,’ 2nd edit.—Idem, ‘Syst. des Annélides,’ 1820.—Schmarda, ‘Neue wirbell. Thiere,’ Bd. i (quoted by Leuckart).—Virey (and Serullas), in ‘Journ. Pharm.,’ 1829, p. 614.—Wagener, in ‘Troschel’s Archiv,’ 1858, Bd. i, s. 244 et seq.—Wahlberg, in ‘Œfvers. Kongl. Vetensk. Akad. Forhand.,’ Stockholm, 1855.
SECTION IV.—Part III.—Arachnida (Pentastomes, Mites, Ticks).
The Trachearian division of the Arachnida comprises a few internal parasites that attack man, and many ectozoa which are parasitic upon man and animals. The species can only be noticed very briefly.
Fig. 50.—Pentastoma tænioides. (1) Male and (2) female, of the natural size. The egg and embryo highly magnified. After Leuckart.
Pentastoma tænioides, Rudolphi.—In the system of classification adopted by Diesing, this entozoon and its allies are placed in the division Cephalocotyleen and therefore, in association with the Cestodes, with which, however, it has no structural affinity. It was long ago pointed out by Van Beneden, T. D. Schubart, Leuckart, and others, that the pentastomes were Acarine and Lernæan Arthropods; the genus being osculant between the Acaridæ and Lernæidæ. The whole subject is discussed in Leuckart’s profound memoir quoted below.