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 38 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 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 
