148 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
taneously. If there were no enteric fever in England, or if all 
enteric cases were rigorously and successfully segregated, and 
all “carriers”? isolated in some way not yet suggested, the 
case against shell-fish as disseminators of the disease would 
have very little force, and interference with the industry 
have no utility or purpose. 
Glucose-fermenting organisms growing in bile-salt broth, 
lactose-fermenting organisms growing on McConkey, Bacillus 
col, “coliform” organisms, or whatever else we call them, 
are indicators of risk only, not actual causes of risk. They are 
assumed to be “ faecal organisms,’ which have entered the 
mussels wa sea-water, sewers and drains, and water-closets 
from the human intestine. If that was where they came from, 
then the actual virulent germs of enteric fever may also travel 
along the same paths and also enter the mussels. Shell-fish 
beds are “closed,” not because the molluscs contain Bacillus 
typhosus, but because, containing “ faecal organisms,” they 
may also contain B. typhosus, which is a faecal organism in 
its most characteristic and significant environment. 
The cogency of a bacteriological case for the closing of a 
mussel bed, or for any other penal restriction or prohibition, 
depends, therefore, on the recognition of organisms infecting 
mussels as truly faecal organisms. They must have come 
originally from the human intestine, or from an animal intestine, 
if there are animals that suffer from enteric fever communicable 
to man, and from no where else. It is useless to show that 
they proceed from street washings, or cattle or horse manure, 
or the faeces of fish and sea-birds, or sewage-contaminated 
soil, unless it is known positively that the germs of enteric 
fever may persist with undiminished virulence in such materials. 
An organism growing on McConkey would have no significance 
for us in this connection, if we could show that it is capable 
of maintaining itself in a medium apart from any possibility 
of contamination with human excreta. 
