Filaria labialis, Pane.—This is a filiform cylindrical worm measuring an inch and a quarter in length. The mouth is armed with four papillæ arranged in the form of a cross. The tail of the female is blunt, the vaginal outlet being placed at a very short distance from its extremity, and a little above or in front of the anus. This parasite was found by a medical student at Naples. It occupied the cavity of a pustule in the upper lip, giving rise to considerable irritation. Only the male worm is at present known.
Bibliography (No. 26).—Davaine, l. c., edit. ii, Synopsis, p. 107.—Leuckart, l. c. (with a fig.), Bd. ii, s. 616.—Pane, “Nota di un elminte nematoide,” in ‘Annali dell’ Acad. degli aspiranti Naturalisti,’ Napoli, ser. 3, vol. iv, 1864.
Filaria hominis oris, Leidy.—In the fifth volume of the ‘Proceedings of the Philadelphia Academy of Natural Sciences’ (1850, p. 117) Dr Leidy furnishes the following description of this worm as gathered from the examination of a simple specimen preserved in alcohol, and labelled as having been “obtained from the mouth of a child.” Body white, opaque, thread-like; mouth round, simple; posterior extremity obtuse, furnished with a short, curved, epidermal hooklet, 1/500″ in length, by 1/2000″ in diameter at base. Dr Leidy offers some speculations as to its origin, but from whatever source the worm was obtained by the bearer, it seems to be an immature form. Its length is five inches and seven lines.
Filaria (Nematoideum) trachealis, Bristowe and Rainey.—This is another very doubtful worm. It was originally described in the ‘Pathological Society’s Transactions’ for 1855. It evidently represents only a juvenile stage of growth of some species of round worm. Rainey discovered a considerable number of these worms in the trachea and larynx of a person who died from a disease affecting the lower extremities. Individually the parasites measured about the 1/50″ in length.
Strongylus (Filaria) bronchialis, Rudolphi.—This is a small nematode. The male measures rather more than half an inch, whilst the female is upwards of an inch in length. The caudal appendage of the male is furnished with a bilobed, membranous, half-bell-shaped bursa. This surrounds the cloacal outlet, the latter concealing a double spiculum. The tail of the female is sharply pointed, the anal orifice being placed a little in front or above. The body is filiform, of a pale yellow color. It is about 1/50″ broad in the male, and 1/35″ in the female. The mode of reproduction is viviparous.
The original specimens were discovered by Treutler in Germany, during the winter of 1791, in the bronchial glands of an emaciated subject, whilst those sent to Diesing for description were discovered by Dr Fortsitz at Klausenberg, in Transylvania, in the lungs of a boy six years old. Diesing and Weinland suggested the identity of Filaria bronchialis and Strongylus longevaginatus, whilst Küchenmeister went further, and pronounced them to be one and the same species.
Bibliography (No. 27).—Cobbold, ‘Entoz.,’ p. 357.—Davaine, ‘Synops.,’ l. c., ‘Synopsis’ cix.—Küchenmeister, l. c., Eng. edit., p. 381.—Leuckart, l. c., s. 618.—Treutler, F. A., “De vermibus filiformibus (Hamularia lymphatica) in glandulis conglobatis bronchiorum repertis,” in ‘Obs. Pathol. Anat.,’ 1793.—Wedl., ‘Die im Menschen vorkommenden Helminthen’ (quoted by Leuckart), Wien, 1862, s. 22.
Eustrongylus gigas, Diesing.—This is by far the largest nematode known to science, the male sometimes measuring a foot in length and the female more than three feet, whilst the breadth of the body reaches half an inch at the thickest part. Though fortunately very rare in man, this worm is known to occur in a great variety of animals, especially in weasels. According to Weinland and Jackson, it is particularly abundant in the kidney of the North American mink (Mustela vison), destroying the substance of the organ, the walls of which become the seat of calcareous deposit. It has been found in the dog, wolf, puma, glutton, raccoon, coati, otter, seal, ox, and horse.
The body of the adult worm is cylindrical, more or less red in color, and somewhat thicker behind than in front. The head is broadly obtuse, the mouth being supplied with six small, wart-like papillæ, two of which correspond with the commencement of the two lateral lines of the body. These lines are also distinguishable from other six longitudinal lines traversing the body from end to end by the presence of very minute papillæ which are less closely arranged towards the centre (Leuckart). The tail of the male shows a simple, thick, cup-shaped bursa, which is destitute of rays, and partly conceals the simple spiculum. The tail of the female is blunt and pierced by the centrally placed anal opening. The vulva is situated near the head in the ventral line. The eggs are stout and oval, measuring 1/300″ in length by about 1/550″ in breadth.
As regards development the recent researches of Schneider have shown that certain kinds of fish play the part of intermediary bearer. Balbiani preserved the ova in water for more than a year without their hatching, and all his attempts to rear the larvæ in the intestines of the dog by direct experiment failed. Similar feeding experiments upon fishes and reptiles also failed. The embryo, when removed from the egg, measures 1/104″ in length. It is vermiform, having a pointed head and simple mouth. Balbiani describes the buccal cavity as containing a protractile stylet. Notwithstanding the negative results obtained by Balbiani’s experiments on fishes, Schneider (from anatomical data, which Leuckart confirms) has placed it almost beyond question that the worm hitherto known as Filaria cystica is the sexually-immature Eustrongylus gigas. This worm is found encysted beneath the peritoneal membrane in Galaxias scriba and Synbranchus laticaudatus. It is worthy of remark that the genus Galaxias comes nearer to the Salmonidæ than to the pike family, whilst the Synbranchi are tropical oceanic fishes. Probably the sexually-immature worm occurs in other fishes, especially the Salmonidæ.