TRANSMISSION OF TROPICAL DISEASES. 17 



the stomach and gut. The sanitary mode of attack then is 

 a simple one, viz., prevention of the contamination of the 

 soil by infected patients. Where primitive hygienic methods 

 still exist the introduction of new methods is always difficult 

 and expensive, but the principle involved is perfectly simple. 

 If sanitation were at a stroke made perfect, the great scourge 

 Ankylostomiasis would be wiped out. The medicinal treat- 

 ment is necessary for the killing of the worms in the infected 

 patients, and except for this purpose would be unnecessary 

 if sanitation were perfect, but as this is far from being so the 

 medicinal mode of attack is still very necessary. It is a 

 question of breaking one link in the chain of the life-history — 

 the thymol kills the adult worm ; improved sanitation prevents 

 the eggs developing in the soil. The chain is in both cases 

 broken. It should be added that the larvae can also infect 

 if they are swallowed, e.g., in drinking water, but whether this 

 mode of infection or that by the skin is the more important 

 remains to be seen. 



Beri-Beri. 



Is a disease characterized by general oedema of the body 

 and various paralytic symptoms. It is common in China, 

 and was responsible for much mortality in the Japanese navy. 

 It is seen in jails, on expeditions, and a form of it occurs on 

 board ship, e.g., a ship put into Birkenhead in 1914 with thirty- 

 three cases on board. It has long been suspected that there 

 was some connection between the disease and eating of rice, 

 but this others denied. It has now been shown that it is 

 only particular kinds of rice that give rise to beri-beri. In fact 

 it is the kind of rice that we consume here daily in our rice 

 puddings, i.e., what one may call a nice clean-looking white 

 rice. Why we do not get beri-beri will appear later. The 

 difference between this rice and the rice in its original form, 



