BACTERIA IN PUBLIC SWIMMING BATHS 91 
Apart from the enormous number of bacteria present in the evening, three points are 
worth noting : — 
o 
1. That Liverpool baths compare very favourably with others in the county 
of Lancashire (vide diagram). 
2. That as a whole first class baths contain fewer bacteria than second class. 
3. The bacteria were more numerous in the fresh water baths than in the 
salt water, partly because they multiplied more rapidly, and partly because the fresh 
water baths were less frequently emptied. 
inn. filwiye Ixdhd 
i/n -the Minima on 
Qgak 37°c 
Liverpool 
1 11 
Lancashire 
Note. — 6,000 should read as 1,500 
We will now briefly consider the source of the bacteria. How is it that the 
clean water in the morning contains very few bacteria, and that in the evening, often 
many thousands ? 
The organisms present in the evening comprise : — (i) Those originally present 
in the clear water ; (2) those derived from the sides of the bath and from the air ; 
(3) those derived from the bodies of the bathers ; (4) those arising by multiplication 
of these organisms during the day. 
The fact that the salt water bath referred to already contained only 46 bacteria 
per c.c. in the morning and fresh water only 500 even after several bathers had 
entered it, prove that the number of organisms introduced from the sides of the bath 
and from the air is relatively insignificant ; consequently the vast majority must be 
derived from the bodies of the bathers or from multiplication. 
In order to determine whether the bacteria carried into a salt bath by the morn- 
ing bathers had multiplied appreciably by the evening, the following experiments 
were performed. 
