128 INFECTIOUS AND PARASITIC DISEASES. 



numbers. As they are voided in process of segmenta- 

 tion, they are easily recognized by examining a drop of 

 feces with the ordinary powers of the microscope. 

 Hatching takes place in water or moist earth, situations 

 in which the embryos may live for months. The larval 

 uncinaria are taken into the body in the drinking-water, 

 or from the hands which have been soiled with earth 

 containing them. 



(/Another mode of entrance is through the skin. The 

 manner in which they get into the bowels is interesting. 

 From the skin the embryos are carried to the right side 

 of the heart and to the lungs. Here they escape from 

 the pulmonary vessels into the air-spaces, travel up the 

 bronchi and larynx into the oesophagus, and by swallow- 

 ing find their way into the stomach and intestines. It 

 is believed that the tropical skin affection known as 

 ^^ground-itch," and which is usually confined to the 

 ankles, is caused by the entrance of embryo uncinaria. 

 In the duodenum and jejunum full development is 

 attained, with subsequent reproduction of eggs. The 

 cycle, it will be observed, is direct. 



The diagnosis rests upon the presence of eggs in the 

 stools. Stiles calls attention to the value of the blotting- 

 paper tests for blood when a microscopic examination 

 cannot be made. Reference is made to this test in the 

 chapter dealing with the examination of the secretions 

 and excretions. 



Expulsion of the parasites is ordinarily successfully 



