36 ECONOMIC ZOOLOGY 



the lung tissue that cause the patient to be unusually susceptible to 

 tuberculosis. 



The question will be asked "How can a comparatively small 

 number of tiny worms cause such a marked anaemia in a full grown 

 human being?" The worms cause their serious effects in two or three 

 ways. The amount of blood actually consumed by them is, perhaps 

 not very serious, but it is supposed that they secrete a substance from 

 glands in the head that prevent clotting of the blood, so that as they 

 move from place to place in the intestine the tiny wounds they leave 

 continue to bleed for some time. Again it is stated by some, that 

 another substance is secreted by the worm that prevents the formation 

 of new corpuscles to replace those that are lost. If both of these 

 substances were at work at the same time the results might be most 

 serious. Still another result of their work is seen in the numerous small 

 sores or ulcers left in the mucosa of the intestine by the bites of the 

 worms. These lesions give many possible points of bacterial infection. 



One hopeful aspect of the disease is the usually easy cure, by the use 

 of two cheap drugs, Thymol and Epsom Salts. They should not be 

 taken without the advice of a physician, and should not be used along 

 with alcohol nor any sort of oil, as the results might be very serious or 

 even fatal. 



It is, of course, chiefly through soil pollution that the disease is 

 spread. Negroes in the south are almost all infected with hookworm, 

 but for some reason, probably from having been infected through 

 long generations in Africa, they are not seriously affected by the parasite 

 and hence are not apt to subject themselves to treatment. As they 

 are notoriously indifferent to sanitary laws, they probably are the chief 

 instruments in the spread of the disease and are the greatest problem 

 in its attempted control. The Rockefeller Hookworm Commission is 

 endeavoring by a campaign of education and wholesale medical treat- 

 ment to eradicate this curse of the south, which if accomplished will 

 go far toward solving many of the economic problems of that region. 

 What treatment and sanitation can accomplish is shown by the 

 change in conditions in the great Bilibid prison in Manila, P. I. " When 

 the Americans took charge of Bilibid prison the death rate was 238 

 per 1000 per year; by improving the sanitary conditions this death 

 rate was reduced to about 75 per 1000; here it remained stationary 

 until it was discovered that a very high percentage of the prisoners 



