34 



is to say, at the same time that the 100 c.c. of the sterile sea 

 water were infected with a given number of B. typhosus, 

 100 c.c. of the non-sterile sea water were infected with the same 

 amount of the same culture of B. typhosus ; 24 hours after, 

 a Drigalski plate was made with a definite amount and the 

 number of typhoid colonies ascertained. It turned out that 

 in the non-sterile sea water the decrease of the number of the 

 B. typhosus was practically the same, viz., between -fa and -^ 7 . 

 It is not necessary to enter here into the details of these 

 experiments, since they were not strictly within the scope of 

 the shellfish inquiry, but the result is clear, viz., that the sea 

 water per se had a powerful destructive action on the B. 

 typhosus. By saying this I do not intend to omit another 

 important fact, viz., that although sea water is capable ot 

 materially reducing already in 24 hours the number of 

 B. typhosus, the reduction does not go on at the same great 

 rate every subsequent 24 hours, for it has been experimentally 

 shown by myself, Professor Herdman, Boyce, and others 

 that in sea water infected with B. typhosus some living 

 individuals can be recovered from large amounts of the water 

 even after many days and weeks. 



We proceed now with our original analyses. 



As mentioned above, the oysters after having been 

 removed from the infected water were placed for 24 hours 

 in sterile sea water in fresh tub ; and this change, both of 

 tub and sterile sea water, was effected every 24 hours. 

 Analyses of the sea water and of one oyster of the "previously 

 wet " and one oyster of the " previously dry " lot were made 

 every 24 hours after change of the sea water, with the 

 following results : 



Sea water of tub one day after change -fa c.c. was used 

 directly for one Drigalski plate ; this yielded a pure culture 

 of B. typhosus, 25 colonies ; that is to say, this sea water 

 contained 250 B. typhosus per 1 c.c., or for the total 

 amount (2000 c.c.) 500,000 B. typhosus. This half-million 

 of B. typhosus in the water in the tub could have been 

 derived solely from the eight infected oysters in it, the sea 

 water having been sterile and the tub having been well 



