eee elle. 
ror 
than this point. By far the most important point is that when 
the rain is prevalent lactis erogenes is distinctly common. 
It may, at this point, be stated that it is extremely 
difficult to show by figures giving percentage prevalence of 
organisms, the actual state of affairs in nature. The figures 
quoted above in a feeble way demonstrate the truth of our 
statements, but any one who works in the laboratory is 
simply astonished at the certainty with which one can predict 
what organisms will be found by knowing the local conditions 
at the time. For instance, even in the Bengal rivers where 
it is more difficult to show the natural prevalence of organ- 
isms, on account of the population on the banks, a sample 
of river water taken in the dry weather from a shallow part 
of the river will invariably contain large number of cloace. 
On the other hand, a river water that is clearing up after the 
polluting influence of a downpour of rain will certainly 
contain large numbers of lactis erogenes. If the pollution 
amounts to a considerable quantity, such as is the case in a 
river Hughli, near Calcutta, it is not possible to show, at any 
rate by figures consisting of percentage prevalence of organ- 
isms, any change in the flora of the water due to variation 
in the seasons. Without forcing these figures in any way, we 
consider that it is legitimate to draw the following conclusions 
from all these results :— 
(1) That resistant organisms do exist in nature, the 
commonest of these is bacillus cloacee, which is always more 
prevalent in the dry weather than in the rains, when it is rare. 
(2) During the time when the rains are common, lactis 
erogenes 1S a very common organism isolated from rivers 
and lakes. 
(3) During the dry weather this organism is rare. 
Hence it is probably not a resistant organism. 
