ENTOZOA. 657 



in man, and chiefly inhabits the small intestines. The male is 

 smaller and more abundant than the female. This worm is 

 white, from six to twelve or fifteen inches long. It is frequently 

 fatal to children, in which it penetrates to the stomach, and even 

 to the mouth. Five hundred have sometimes been passed from 

 a child in the course of seven or eight days ; also Pin-Worms or 

 Thread Worms, A. vermicularis, (Lat. from vermiculus, a little 

 worm.) These are very minute, the male seldom exceeding 

 two lines, and the female five lines in length, and being propor- 

 tionally slender.* They dwell in the large intestines, sometimes 

 in immense numbers and producing great irritation. 



2. Filaria, (including the GUINEA WORMS,) of which three 

 species inhabit the human body. Some are found in various 

 animals including insects and their larvae. These are long worms, 

 smooth and thread-like, and of a somewhat rigid texture. The 

 GUINEA. WORM, F. Medinensis, occurs in Arabia, Upper Egypt, 

 Guinea, the West Indies, and other hot climates. It is generally 

 white, but sometimes of a brown color. The length varies from 

 six inches to twelve feet, and it is about as thick as the string of 

 a violin. It infests the muscles and subcutaneous tissues, prin- 

 cipally of the lower limbs ; sometimes it locates itself about the 

 eye and under the tongue. Occasionally it makes its way to 

 the surface of a skin, creating a pustule or sore, when it may be 

 taken hold of and cautiously and gradually extracted. If broken 

 off, however, the part remaining enclosed produces inflammation, 

 and may render amputation indispensable. Within the tropics, 

 people sometimes seem to be affected by it almost epidemically, 

 nearly half the men in a regiment of soldiers, having at the same 

 time been attacked by it. It seems that it may exist under the 

 skin many months or even a year without being detected. The 

 Guinea worm is said to be sometimes seen swimming in the wa- 

 ters of the countries which it inhabits. 



Species of the Filaria have recently been found in the blood 

 of dogs. The HAIR-WORMS, Gordius aquations, (see Chart,) 

 are nematoids found in free water, or as internal parasites of 

 insects. The latter swallow the eggs of the Hair Worm, after 

 they have been deposited in water; and "in this position the egg 

 is hatched, producing the Gordius, which becomes impregnated, 

 and escapes from the insect into waters where it deposits its eggs." 

 It has erroneously been supposed to be developed from a horse 

 hair. 



* The line here referred to is the twelfth part of a French inch. 



