BIOLOGY OF BACTERIA. 59

are ready for absorption. It seems probable that the
absorption of the toxic substances by reducing the vital-
ity of the individual predisposes to the formation of local
lesions through which the bacteria may enter the intes-
tinal walls to continue their existence and produce
greater damage than before. Some such theory may
explain the activity of such organisms as those of
typhoid, cholera, and meat-poisoning, but it is not true
that all bacteria can be admitted into the intestinal struc-
ture in this way, for the experiments of Max Neisser,1 who
fed mice, guinea-pigs, and rabbits upon a variety of
pathogenic and non-pathogenic bacteria, both before and
after injuries to the intestine caused by the ingesticm of
powdered glass, chemical agents, and irritating bacteria,
failed to show that with the exception of those bacteria
whose particular tendency is toward the production of
intestinal disease, none entered either the chyliferous
system, the blood-vessels, or the organs.

The occurrence of the staphylococcus aureus and other
bacteria in osteomyelitis, and of tubercle bacilli in deep-
seated diseases of the bones and internal organs, has led
many to believe that the intestine is a point of easy
entrance. There is, however, no reason to believe that
penetration of the digestive mucous membrane is any
easier than that of the respiratory or other similarly deli-
cate tissues.

On the other hand, Beco2 is of the opinion, that, with-
out any apparent lesion of the intestine, bacteria—ba-
cillus coli—escape from it into the blood during life,
His experiments showed that immediately after death the
colon bacillus could be found iti small numbers in the
spleen, in many cases. After twenty-four hours, in
three cases, they were present in immense numbers.
When, however, they were absent from the organ im-
mediately after death, they were also absent after twenty-
four hours.

1 Ztitschrift fur Ifygiene, June 25, 1896, Bd. xxii., Heft I.

2 Ann. (te rinst. Pasteur, 1895, No. 3.