. Animal biology. Zoology; Biology. PHYLUM NEMATHELMINTHES 181 meat whenever found. Even infected meat, however, would not be dangerous if it were thoroughly cooked. An undesirable practice which formerly prevailed on farms in some localities was to leave dead animals exposed where living animals could eat them. It is better to burn such carcasses or to bury them so deep that animals cannot reach them. 213. Filaria.—The nematodes known as filariae include a number of species which affect both man and domestic animals, particularly in the tropics. The most injurious type is Wuchereria hancrofti
. Animal biology. Zoology; Biology. PHYLUM NEMATHELMINTHES 181 meat whenever found. Even infected meat, however, would not be dangerous if it were thoroughly cooked. An undesirable practice which formerly prevailed on farms in some localities was to leave dead animals exposed where living animals could eat them. It is better to burn such carcasses or to bury them so deep that animals cannot reach them. 213. Filaria.—The nematodes known as filariae include a number of species which affect both man and domestic animals, particularly in the tropics. The most injurious type is Wuchereria hancrofti (Cobbold), which is a threadworm living in the lymphatic system of man. The larvae of this parasite are carried about in the blood, retreating to the center of the body in the daytime but at night migrating to the peripheral blood vessels in the skin. At times the adults exist in such num- bers as to obstruct the passage of the lymph and cause a swelling of the limbs and other parts of the body, which suggests the name of the resulting disease, elephantiasis. At night, when the larvae are active and are in the peripheral vessels, they are sucked up by mosquitoes. They continue their development for a time in the mosquito's body and when the mosquito bites another person are transmitted to him. Elephantiasis is a very serious disease, particularly in the South Sea Islands. 214. Hairworms,—A worm which is popu- larly known as the horsehair snake, and which is believed by many ignorant of zoology to be produced in water from the hairs of horses, is by most authors placed in this phylum. The class to which this worm belongs, known as the ^^'Y ^ «?«^^'"^'^ °^ Gordius. Gordiacea, and of which the type genus is Gordius, includes several forms, some occurring in fresh water and others being marine. The hfe histories of these is not well known. The egg is laid in the water and from it hatches a larva with a large proboscis and hooks at the anterior end. Using these in borin
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