Suppuration of operative and accidental wounds was, until recently, supposed to be essential. We now know, however, that wounds will not suppurate if kept perfectly free from one of the dozen forms of bacteria that are known to give rise to the formation of pus.

The doctrine of present surgical pathology is that suppuration will not take place if pus-forming bacteria are kept out of the wound, which will heal by first intention without inflammation and without inflammatory fever.

In making this statement I am not unaware that there is a certain amount of fever following various severe wounds within twenty-four hours, even when no suppuration occurs. This wound fever, however, is transitory; not high; and entirely different from the prolonged condition of high temperature formerly observed nearly always after operations and injuries. The occurrence of this "inflammatory," "traumatic," "surgical," or "symptomatic" fever, as it was formerly called, means that the patient has been subjected to the poisonous influence of putrefactive germs, the germs of suppuration, or both.

We now know why it is that certain cases of suppuration are not 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 tendencies. The attempt was unsuccessful and unsatisfactory. The reason is now clear, because it is known that the brunette or the blond, the old or the young, may become infected with the tubercle bacillus. Since the condition depends upon whether one or the other become infected with the generally present bacillus of tubercle, it is evident that there can be no distinctive diathesis. It is more than probable, moreover, that the cutaneous disease so long described as lupus vulgaris is simply a tubercular ulcer of the skin, and not a special disease of unknown causation.

The metastatic abscesses of pyaemia are clearly explained when the surgeon remembers that they are simply due to a softened blood clot containing pus-causing germs being carried through the circulation and lodged in some of the small capillaries.

A patient suffering with numerous boils upon his skin has often been a puzzle to his physician, who has in vain attempted to find some cause for the trouble in the general health alone. Had he known that every boil owed its origin to pus bacteria, which had infected a sweat gland or hair follicle, the treatment would probably have been more efficacious. The suppuration is due to pus germs either lodged upon the surface of the skin from the exterior or deposited from the current of blood in which they have been carried to the spot.

I have not taken time to go into a discussion of the methods by which the relationship of micro-organisms to surgical affections has been established; but the absolute necessity for every surgeon to be fully alive to the inestimable value of aseptic and antiseptic surgery has led me to make the foregoing statements as a sort of résumé of the relation of the germ theory of disease to surgical practice. It is clearly the duty of every man who attempts to practice surgery to prevent, by every means in his power, the access of germs, whether of suppuration, putrefaction, erysipelas, tubercle, tetanus, or any other disease, to the wounds of a patient. This, as we all know, can be done by absolute bacteriological cleanliness. It is best, however, not to rely solely upon absolute cleanliness, which is almost unattainable, but to secure further protection by the use of heat and antiseptic solutions. I am fully of the opinion that chemical antiseptics would be needless if absolute freedom from germs was easily obtained. When I know that even such an enthusiast as I myself is continually liable to forget or neglect some step in this direction, I feel that the additional security of chemical antisepsis is of great value. It is difficult to convince the majority of physicians, and even ourselves, that to touch a finger to a door knob, to an assistant's clothing, or to one's own body, may vitiate the entire operation by introducing one or two microbic germs into the wound.

An illustration of how carefully the various steps of an operation should be guarded is afforded by the appended rules, which I have adopted at the Woman's Hospital of Philadelphia for the guidance of the assistants and nurses. If such rules were taught every medical student and every physician entering practice as earnestly as the paragraphs of the catechism are taught the Sunday school pupil (and they certainly ought to be so taught) the occurrence of suppuration, hectic fever, septicaemia, pyaemia, and surgical erysipelas would be practically unknown. Death, then, would seldom occur after surgical operations, except from hemorrhage, shock, or exhaustion.