50 



increase ; and for these reasons alone, cockles coming from a 

 polluted locality require, for their being rendered safe, a 

 thorough and careful disinfection by heat such as was 

 indicated above, viz., steaming under pressure for at least 

 three minutes. 



Table V gives the summary of Experiment V. 



TABLE V. 



Cockles kept in sea water infected with B. typhosus to 

 the amount of four millions per 1 c.c. 



Cockle 1 24 hours in infected sea water, contained about 



500,000 B. typhosus. 

 2 after 1 day's change in clean wet sand, contained 



about 153,000 B. typhosus. 

 ,, 4 after 2 days' change in clean wet sand, contained 



about 382,000 B. typhosus. 

 6 after 5 days' change in clean wet sand, contained 



about 358,000 B. typhosus. 

 ?) 8 after 6 days' change in clean wet sand, contained 



about 1,541,000 B. typhosus. 

 10 after 7 days' change in clean wet sand, contained 



about 138,000 B. typhosus. 

 12 after 9 days' change in clean wet sand, contained 



about 69,300 B. typhosus. 

 12a after 9 days' change in clean wet sand, contained 



about 111,000 B. typhosus. 

 " 14 after 10 days' change in clean wet sand, contained 



about 1600 B. typhosus; abnormal. 

 5) 14-a after 10 days' change in clean wet sand, contained 



about 69,000 B. typhosus. 



EXPEEIMENT VI. 



Several dozen fresh mussels were well cleaned under the 

 tap and were then placed in sterile sea water in a clean 

 tub, to which an emulsion of pure culture B. typhosus 

 was added to the amount of 5,170,000 B. typhosus per 



