THE MICROBES OF HUMAN DISEASES. 169 



the lower part of the town, situated on the banks of 

 the Speyerbach. There was a hospital for old men, 

 situated in the high part of the town, a quarter which 

 remained free from cholera, but 24 out of the 200 

 pensioners whom the hospital contained were attacked 

 by the disease. Now 33 of these men, the most able- 

 bodied among them, had been employed to dig up 

 some blighted potatoes in a field which lay very low, 

 almost on a level with the water which had collected 

 in a deserted sand-pit. They had not drunk of the 

 water in this field, neither had they passed through 

 the part of the town visited by the epidemic : 20 out 

 of these 33 men had cholera, and only 4 others out of 

 all the inmates of the hospital contracted the disease" 



Observations made on board English transports 

 on the voyage from India give analogous results. 

 ".Detachments of equal number from two regiments 

 embarked on the same steam transport. A few days 

 later, cholera declared itself and carried off many 

 soldiers, all belonging to one of the two regiments, 

 and coming from a camp in which there was a violent 

 outbreak of cholera shortly after their departure. The 

 detachment from the other regiment, coming from a 

 place exempt from cholera, altogether escaped." Here 

 the influence of the locality and the soil is evident ; it 

 was the sole and essential agent of the disease, since 

 the contagion could not have occurred on board ship, 

 in which the conditions are generally healthy, neither 



