The trematodes are solid worms of a tongue or leaf shape. They possess a clinging apparatus in the form of oral and ventral sucking-cups varying in number. Sometimes they are also provided with hook or clasp like projections for this purpose. The intestinal canal is without any anus and is split like a fork nearly throughout its extent. The fluke worms are mostly hermaphroditic. To these belong:

Distoma Hepaticum Or Liver Fluke

This parasite has a leaf shape, is 22 mm. long and 12 mm. wide. The cephalic end projects like a beak and bears a small cuplike sucker, in which the mouth is located. Close behind this on the ventral surface is a second suction cup and between the two lies the sexual orifice. The uterus consists of a convoluted bulb-shaped bag. situated behind the posterior sucker. On each side of the body lie the ovisacs and between them the much branched testicular canals (see Fig. 50). The eggs are oval, 0.13 mm. long and 0.08 mm. wide. They have a brownish color and are provided with a lid (Fig. 51).

Distoma Hepaticum

Fig. 50. - Distoma Hepaticum. with Male and Female Sexual Apparatus. (Leuckart.)

Magnified 2 1/2 diameters.

Eggs of Distoma Hepaticum

Fig. 51. - Eggs of Distoma Hepaticum. (Leuckart.) Magnified 200 diameters.

The liver fluke is rare in man, though frequently found in ruminating animals. It inhabits the biliary ducts and is occasionally found in the intestine and in the inferior vena cava. The symptoms which it produces are varied: jaundice, enlargement of the liver, diarrhoea, hemorrhages.

Distoma Lanceolatum with its Inner Organs.

Fig;. 52. -Distoma Lanceolatum with its Inner Organs. (Leuckart.) Magnified 10 diameters.

Most probably the liver fluke reaches the intestinal canal by means of impure water or vegetables.

Distoma lanceolatum is 8 to 9 mm. long and 2 to 2.5 mm. wide. It has a lancet shape and the head portion is not specially marked off from the body (Fig. 52). The eggs are considerably smaller than those of distoma hepaticum, being only 0.04 mm. long (Fig. 53). With regard to its. occurrence and symptoms it resembles the liver fluke.

Distoma haematobium or Bilharzia hoematobia is frequently found in hot climates, especially in Egypt. In the United States and in Europe it is very rarely found. This parasite has separate sexes. The male is from 12 to 14 mm. long. Its body is smooth, but in its posterior portion rolled up into a tube, which serves for the reception of the female (canalis gynaecophorus) (Figs. 54 and 55). The female is from 16 to 19 mm. long and almost cylindrical. The sexual opening lies in both sexes close behind the ventral sucker. The distoma haematobium finds its way into the intestinal canal of man and then reaches the portal circulation, where it develops. In the intestinal canal it has been encountered very rarely, in which case ulcerations of the intestinal mucosa were present. It frequently causes haematuria and great cachexia, terminating fatally in some instances.

Egg of Distoma Lanceolatum Shortly After the Formation of a Shell

Fig. 53. - Egg of Distoma Lanceolatum Shortly After the Formation of a Shell. (Leuckart.) Magnified 100 diameters.

Distoma Haematobium

FIG. 54.

Eggs of Distoma Haematobium

FIG. 55.

Fig. 54. - Distoma Haematobium. (Leuekart.) Male and .female, the latter in the canalis gynaecophorus of the former. Magnified 10 diameters. Fig. 55. - Eggs of Distoma Haematobium. (Leuckart.) a. Egg with terminal spine; b, egg with lateral spine. Magnified 150 diameters.

As regards treatment, the removal of these fluke worms must be undertaken in identically the same manner as that of the tapeworms described above.