36 



being used for one Drigalski plate. The plate remained free 

 of any colonies. 



Oyster 19, previously wet, after two days' changes total 

 amount of fluid, 3 5 c.c. ; -j^ c.c. yielded three colonies of 

 B. typhosus this amounts to 105 B. typhosus per oyster. 



Oyster 20, previously dry, after two days' changes total 

 amount of fluid, 3 5 c.c. ; ^ c.c. yielded 19 colonies of 

 B. typhosus this amounts to 646 B. typhosus for the whole 

 oyster. 



Sea water after third change yielded likewise no B. 

 typhosus per -fa c.c. 



Oyster 21, previously wet, after three days' changes total 

 amount, 2*6 c.c. ; fa part of oyster yielded no colonies of B. 

 typhosus. 



Oyster 22, previously dry, after three days' changes 

 total amount, 2*3 c.c.; fa c.c. yielded 31 colonies of B. 

 typhosus this amounts to 713 B. typhosus for the whole 

 oyster. 



The sea water was analysed after fourth and sixth 

 changes ; -fa c.c. direct yielded no colonies. 



Of the oysters only two were left of the previously wet 

 lot, viz., oyster 23 and 25 ; neither of them yielded any colonies 

 of B. typhosus in fa part of oyster. 



It will be noticed in this series that two days after change 

 the sea water per fa c.c. did not contain any B. typhosus ; at 

 this stage there were six oysters four previously wet, two 

 previously dry in the water ; assuming that all previously 

 wet and dry oysters contained, when placed in this sea water 

 24 hours previously, the same number of B. typhosus, viz., 

 935 and 1900 respectively, the total number of B. typhosus 

 assumed to be in these six oysters would only have amounted 

 to 7540, so that in 2000 c.c. of the surrounding water, even 

 assuming that the whole of B. typhosus were passed out into 

 the water, it would have only amounted to between three 

 and four B. typhosus per 1 c.c. ; in fa c.c., therefore, none 

 would have been detected. 



Tabulating the results of this Experiment III : 



