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" 

 (Nageli). 



Observations made on board Fnglish 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 'vhich the conditions are generally healthy, neither 



