circumscribed but diffuse, so that the pus dissects up the fascias and
muscles and destroys with great rapidity the cellular tissue. This
form of suppuration is due to a particular form of bacterium called
the pus-causing "chain coccus." Circumscribed abscesses, however, are
due to one or more of the other pus-causing micro-organisms.

How much more intelligent is this explanation than the old one that
diffuse abscesses depended upon some curious characteristic of the
patient. It is a satisfaction to know that the two forms of abscess
differ because they are the result of inoculation with different
germs. It is practically a fact that wherever there is found a diffuse
abscess there will be discovered the streptococcus pyogenes, which is
the name of the chain coccus above mentioned.

So, also, is it easy now to understand the formation of what the old
surgeons called "cold" abscesses, and to account for the difference in
appearance of its puriform secretion from the pus of acute abscesses.
Careful search in the fluid coming from such "cold" abscesses reveals
the presence of the bacillus of tuberculosis, and proves that a "cold"
abscess is not a true abscess, but a lesion of local tuberculosis.

Easy is it now to understand the similarity between the "cold abscess"
of the cervical region and the "cold abscess" of the lung in a
phthisical patient. Both of them are, in fact, simply the result of
invasion of the tissues with the ubiquitous tubercle bacillus; and are
not due to pus-forming bacteria.

Formerly it was common to speak of the scrofulous diathesis, and
attempts were made to describe the characteristic appearance of the
skin and hair pertaining to persons supposed to be of scrofulous