THE MICEOBES OF HUMAIf DISEASES. 207 



ducing the attenuated microbe into the stomach by 

 means of pills or a liquid, would not be more rational. 



Mode of Propagation and Persistence of Cholera. — 

 The upper part of the delta of the Ganges seems to 

 be the original home of cholera and its microbe. 

 Below this region, the stagnant water on each side 

 of the river, infected with every species of ordure, 

 renders the maritime base of the delta whoUy unin- 

 habitable. But even in its upper part the land is 

 nearly covered by water. In order to build a house, 

 the earth is heaped up to raise the level of the soil, 

 and the house stands on the embankment, surrounded 

 by water. A high temperature is necessary to enable 

 the bacUlus to live in water, and it is probable that it 

 wiU never become acclimatized in our colder climate. 

 The drainage which has been carried on round Cal- 

 cutta has already rendered epidemics less serious. 



The disease is always propagated by man. In 

 India, Arabia, and Egypt, its diffusion is chiefly owing 

 to pilgrimages. In Bengal the pilgrims aU bathe 

 together in sacred pools, often only a few square 

 metres in size, and receiving some thousands of men 

 in the course of the day, streaming with sweat and 

 exhausted by long journeys and insufficient food, and 

 under such conditions cholera is often developed. 

 From India it passes to Arabia by means of the 

 Mussulman pilgrims, whose caravans block the nar- 

 row streets of Mecca every year^ and thence it is trans^ 

 ported to Egypt. Finally, it is carried from Alexandria 



