NEMATHELMINTHES 93 



ashes, tobacco, paper, plaster. Hookworm disease may be mistaken 

 for anemia as the red corpuscles are deficient in number. The eggs 

 pass out in the feces and if allowed to get into the soil will develop 

 into tiny worms. Larvae of the hookworm enter the feet, boring 

 through the skin into lymph spaces, thence via the lymph vessels 

 to the veins and into the heart. The heart pumps them through 

 the pulmonary arteries to the lungs. From the lungs (where they 

 form lesions) they travel up the bronchi and trachea to the pharynx 

 and are swallowed down the esophagus and into the stomach and 

 intestine. They may come directly into the intestine from the mouth 

 and esophagus, if taken in with dirty water or food. In the intestine 

 they do not multiply, but the females continuously produce ova 

 remaining there sometimes for three years. Nicoli showed (1917) 

 that hookworm larvae will live in water for eighteen months, but 

 Ackert found (1924) that at the end of that time, they were no longer 

 infective.^ Ackert also discovered that larvae will live in water 

 ranging from 45° to 98° F. The similar European hookworm {Ancy- 

 lostoma duodenale), found first in English Egypt, is about 2/5 of an 

 inch long, living in the small intestine of man. 



Ancylostoma braziliense., a worm infesting the small and rarely 

 the large intestines of the cat, dog and fox, is the cause of " ground 

 itch " in Southern United States. Reference has been made 

 (page 88) to the important study of Wells (1931) on anemia pro- 

 duced by the dog-hookworm. 



Through the activity of Dr. C. W. Stiles, U. S. P. H. S., and his 

 co-workers in the Rockefeller Sanitary Commission,^ the hookworm 

 is now being controlled in the United States and approaching 

 control elsewhere. Dr. Stiles has pointed out (Scientific Monthly, 

 October, 193 1, vol. 2>3^ PP- 362-364) that hookworm disease is even 

 now one of the most important causes of backwardness in southern 

 school-children. 



Family 4. Trichuridae. — These nematodes, placed under the 

 family Trichinellidae by some writers, are called the " hair necks," 

 as they have a long slender anterior portion which contains 

 the esophagus. The head is nude and the mouth rounded. They 

 are oviparous. 



2 Ackert, J. E. 1924. Studies on the longevity and infectivity of hookworm 

 larvae. Am. Jour, of Hyg., vol. 4, no. 3, pp. 222-225. 



' Cort and his associates, in the International Health Board, have published more 

 than thirty papers on hookworm disease, chiefly in the Am. Jour, of Hygiene. 



