MAN AS FOOD FOR ANIMALS 43 



in another in the later stages. There are numerous different 

 kinds in man some of which are very long, up to 30 feet or 

 more, and others very small, less than an inch. Most of 

 them are also known as parasites in cattle, hogs, dogs, rats, 

 mice or other animals, with the early stages in insects, crus- 

 taceans, lish, frogs, snakes, mammals, etc. Various larval 

 tapeworms have been found in man of which the adults have 

 not been determined. One larval tapeworm found in man is 

 the young of a dog tapeworm; this would promptly develop 

 in any dog if it ate the flesh of an infected man. Ordinarily 

 dogs become infected from eating carcasses or offal from sheep 

 and cattle which also harbor the larval worms. 



Of the extremely numerous sorts of round-worms 59 species 

 are listed as having been found in man, some of which are 

 dangerous parasites, some relatively harmless, and some merely 

 casual or accidental. 



The most important of the round-worms as human parasites 

 and a terrible menace to health and efficiency in most of the 

 warmer regions are two sorts of hookworms which live in the 

 intestines and enter the body by boring through the skin, 

 usually of the feet and legs. The eel-worm, which sometimes 

 measures as much as i8 inches in length, is also a serious pest 

 in many places, especially in children, as is the trichina which 

 is contracted from eating uncooked or insufliciently cooked 

 pork. The various filarial worms, some causing elephantiasis, 

 so common in many tropical lands, belong to this group. 

 They are transmitted by certain mosquitoes, tabanids, etc. 

 The largest of the round-worms are the Guinea-worms which, 

 from 3 to 5 feet in length, live beneath the skin. When young 

 they Hve in those httle water fleas called copepods. 



A few sorts of the so-called spiny-headed worms sometimes 

 occur in the intestinal tract of man. 



Within the human intestines live quite a large number of 

 different protozoans — amoebas, flagellates and ciliates — which 

 under a microscope recall the similar forms occurring in hay 

 infusions. These animals are able to form about themselves 



