516 Profs. Percy Frankland and Marshall Ward. 



The above three tables are of especial importance, exhibiting as 

 they do the different behaviour of the typhoid bacillus taken from 

 one and the same cultivation and in approximately the same numbers, 

 on being introduced into these three different kinds of water in their 

 natural unsterilised condition. 



From the first table it will be seen that in the Thames water the 

 typhoid bacilli were demonstrable on 28.10.1893, i.e., nine days after 

 their introduction, but already four days later, and afterwards, all 

 endeavours to discover the typhoid bacillus proved abortive. 



From the second table, on the other hand, it will be seen that in 

 the Loch Katrine water the presence of the typhoid bacillus was demon- 

 strable on 7.11.1893, i.e., nineteen days after its introduction, whilst 

 on 21.11.1893, or fourteen days later, and afterwards, it could no more 

 be discovered. 



From the third table, again, it will be seen that in the deep-well 

 tvater the typhoid bacilli were easily discoverable on 7.11.1893, i.e., 

 nineteen days after their introduction, and just discoverable on 

 21.11.1893, or thirty-three days after their introduction, whilst, six 

 days later and thereafter, all attempts to demonstrate their presence 

 proved fruitless. 



As regards the effect of agitation in these experiments, it appears 

 that the agitation on the whole promoted the multiplication of the 

 water bacteria in the unsterilised waters, whilst it somewhat acceler- 

 ated the disappearance of the typhoid bacilli in the infected sterile 

 waters. These results partially confirm those obtained by Professor 

 Bay Lankester in some similar experiments described by him to the 

 recent Royal Commission on the London Water Supply (Appendix, 

 p. 455). 



In his experiments 2 litres of sterilised river water were placed in 

 two similar jars, and each was similarly infected with the typhoid 

 bacillus. One of the jars was then syringed four times an hour for 

 twelve hours, and, after an interval, for eight hours more. The other 

 jar was left undisturbed in the dark. The syringed jars showed a 

 very marked inferiority in the number of typhoid germs obtained 011 

 cultivation, amounting to a reduction of one-half. 



In my experiments the difference between the waters kept at rest 

 and those submitted to agitation was not nearly so marked, which 

 may possibly be due to the different mode of agitation employed, and 

 also to the fact that the waters were not examined so soon after 

 the agitation, for it is quite possible that the combined effect of 

 agitation and oxygenation makes itself felt more in the first in- 

 stance than later on. 



In the case of the infected unsterilised waters, again, there is 

 considerable evidence that the agitation hastened the disappearance 

 of the typhoid bacilli. Thus in the case of the unsterile Thames water, 



