33 



The sea water had been infected with B. typhosus to the 

 amount of 2,360,000 B. typhosus per 1 c.c., and as there 

 were 2000 c.c. of the sea water, we have then 2,360,000 X 

 2000. 



4,720,000,000 B. typhosus had been originally present in 

 the 2000 c.c. of the sea water in the tub in which the oysters 

 were placed ; the ten oysters had therefore removed in 24 hours 

 from this total only 5,776,000 B. typhosus, so that there should 

 have remained in the tub after 24 hours nothing else happen- 

 ing a little over 4660 millions of B. typhosus. But accord- 

 ing to our analysis the sea water in the tub after 24 hours 

 contained only 126,000 B. typhosus per 1 c.c., that is, 

 126,000 X 2000 for the total; that is to say, the total sea 

 water now 24 hours after infection contained only 252 

 millions of B. typhosus. The number of B. typhosus in the 

 sea water in the tub must have suffered a decrease from 

 4660 millions to 252 millions, that is, not more than -fa part 

 of the original number were left. There are no data as to 

 an active destruction of B. typhosus going on in the oysters 

 during the same 24 hours, but we may, without much danger of 

 error, assume that the chief destruction of the microbes was 

 going on in the sea water itself. The sea water was, before 

 being infected, sterile sea water; the oysters yielded no 

 microbes except B. typhosus taken in from the infected water. 

 It follows from this that the just named rapid destruction in 

 the sea water in the tub could not have been caused by 

 the presence of other microbes, but must be referred to an 

 inimical action of the sea water itself. This was proved 

 directly by experiment ; 100 c.c. of sterile sea water were 

 infected with a given number of the same B. typhosus and 

 kept for 24 hours. The analysis showed that the diminution 

 amounted to -f- r , against the figure ^ found in the above 

 experiment. To show that this inimical effect of our sterile 

 sea water was not due to the sterility of the sea water, but to 

 the sea water as such, the experiment was made by comparing 

 in a parallel series the effect of non- sterile sea water exactly 

 as it had been received from the same portion of the sea 

 (Lowestoft) from which all our sea water was obtained that 



D 



