ANIMAL PARASITES. 139 



Stronffyhis gigas. This is a slender red worm, the female being some- 

 times 1 metre long and over 1 cm. in diameter. It has been found 

 several times in the pelvis of the kidney in man. It is more common in 

 the wolf, fox, horse, seal, and some other animals. 



Strongylus longevaginatus. The female is about 2.5cm. long, the male, 

 as usual, shorter. It is of a yellowish-white color, and has been found 

 once in the lung of a boy in Germany. 



Strongylus subtilis. A very small species (female 5.6-7 mm. long) has 

 been described by Loos as occurring in Egypt in the human intestine. 

 But it is believed to be without pathological significance. 



Dochmius duodenalis (Aukylostoma duodenale). The female is from 

 1 to 2 cm. long, the male about 1 cm. long. The body of the male is 

 dilated anteriorly and curved backward. Its mouth is furnished with 

 a chitiuous capsule and chitiuous claws and teeth. It is found in the 

 small intestine of man in Italy, Switzerland, Egypt, and Brazil. The 

 head is burrowed into the mucous membrane of the host, and the animal 

 is nourished by the blood which it sucks out, and which is usually seen 

 in its intestine. An ecchymosis is produced at the point of attachment, 

 or even severe haemorrhage, and marked anaemia may be the result of 

 the presence of large numbers of the parasites. 



Trichocephalus dispar (Whipworm. ) The males and females are of 

 nearly equal size, 4 to 5 cm. long. A little less than one-half of the 



body (the posterior portion) is about 1 

 mm. thick, and in the male is rolled into 

 a flattened spiral, but in the female is but 

 slightly bent. The anterior part of the 

 body is very slender (Fig. 66) and is em- 

 bedded in the mucous membrane of the 



FIG. W.-TBICHOCKFHALC8 D.SPAR. ^ ^ ^ ^ ^ ^ 



From the skin of the mons veneris. 



shaped, about 0.05 mm. long and about 



one-half as wide, with a thick brown capsule. This parasite is very 

 common in some countries, especially in France and southern Italy. It 

 is commonly found in the csecum, usually in small, but sometimes in 

 very large, numbers. It is generally of little pathological significance, 

 commonly producing no symptoms. Its developmental history is not 

 well known. 



Trichina spiralis. The female of this common parasite is, in the ma- 

 ture condition, about 3 mm. long, the male from 1 to 1.5 mm. long; they 

 are filiform in shape and white in color. The young are born in the 

 form of tiny worms about 0.01 mm. in length and somewhat similar to 

 the adult in shape. Infection occurs in man from the ingestion of in- 

 sufficiently cooked pork. The muscle of the diseased pig contains the 

 embryos of the parasite in an encysted condition. In the stomach the 

 capsule of the worm is dissolved and the embryos are set free. They 

 very rapidly mature, increasing in size, and the females give birth in 

 the small intestine to very large numbers of young. It is estimated that 

 a single female may give birth to from 1,300 to 1,500 young. These find 



