MICRO-ORGANISMS AS PARASITES. "25 



of 1S17 originated, lies on the borders of this vast, infectious 

 marsh, and Calcutta, which is now the fixed home of cholera, is 

 connected with the neighbouring Sunderbuns, by a marshy tract 

 of land. 



From its original home the cholera is carried by the enormous 

 bands of pilgrims, who travel yearly to the sacred cities of India, 

 and by the Mahometan pilgrims it is carried to the sacred cities 

 of Arabia. Here the tide of pilgrims from India meets the tide 

 of yearly pilgrims from Egypt and other Mahometan countries, 

 and thus the infection reaches the Levant, and thence spreads to 

 every European seaport where it can find a congenial resting- 

 place. I was once in the midst of a severe epidemic of cholera 

 at Gibraltar, in 1865. We watched the advance of the disease ; 

 first it was heard of at Cairo, then at Alexandria, next it appeared 

 at Malta, and we felt the turn of Gibraltar would come next. A 

 regiment, apparently uninfected, came from Malta ; it camped on 

 the neutral ground, a narrow neck of land connecting the rock 

 with the Spanish mainland. In a fortnight the regiment embarked 

 for the Cape, and in ten days' time cholera broke out violently in 

 Gibraltar, and (as we afterwards heard) broke out on board ship in 

 the regiment which was on its way to the Cape. I was much 

 struck at the time with the fact that no officers, or their wives, or 

 their children were attacked, though the poor soldiers died like 

 flies. The food of all inhabitants of the rock came from the 

 same market ; whence then came the immunity of the officers 

 and their families ? Our loater supply was perfectly distinct ; we 

 drank rain-water collected in tanks, removed from all possible 

 contagion by drainage. It was impossible, even then, not to arrive 

 at the conclusion that an uncontaminated water supply was the 

 secret of our escape, though our knowledge at that date could 

 only be empirical. 



To return for a moment to the Hindu pilgrims. They are 

 crowded for weeks together by thousands in the narrowest space ; 

 the same tanks serve for drinking, bathing, and washing clothes ; 

 and under these circumstances who can wonder that cholera, 

 when once developed amongst the pilgrims, travels quickly over 

 the whole of India ? This source of evil has of late years 

 been much diminished by the stringent sanitary regulations of the 

 Indian Government. 



