disease and requires the same measures of protection against mosquitoes. On the assumption that mosquitoes remain in the vicinity of their breeding places, or never travel far, the prevalence of malarial fever at a post would indicate want of proper care and diligence on the part of the surgeon and commanding officer in complying with General Orders No. 6, Department of Cuba, 1900.

"7. Surgeons are again reminded of the absolute necessity, in all fever cases, to keep, from the very beginning, a complete chart of pulse and temperature, since such a chart is their best guide to a correct diagnosis and the proper treatment.

"BY COMMAND OF MAJOR-GENERAL WOOD.

"H. L. SCOTT,
"Adjutant-General."

The practical execution, in the city of Havana, by Major1 Gorgas, Surgeon U. S. A., chief sanitary officer of the city during its occupation by our troops, of the measures indicated in the above circular was attended with entire success. For more than two years this city has been entirely free from cases of yellow fever, while for many years prior to the date when Major Gorgas inaugurated his war upon infected mosquitoes the disease had prevailed to a greater or less extent annually and a certain number of deaths had occurred every month in the year.

Now Colonel Gorgas, by special act of Congress, as a reward for his services.

CHAPTER XVIII

WOUND INFECTIONS

ERTAIN of the diseases heretofore considered

CER

may be communicated to man by inoculation and are occasionally contracted by the accidental inoculation of wounds or abrasions. Thus we may have a tubercular infection of the skin ("lupus") extending sometimes to adjacent lymphatic glands, or a localised diphtheritic process, upon any portion of the surface of the body. But in the present chapter we propose to consider certain localised or general infectious diseases which as a rule have their origin through the accidental introduction of pathogenic bacteria into an open wound or upon an abraded surface. Before the days of antiseptic surgery such accidental inoculations were much more frequent than at present. Erysipelas, hospital gangrene, suppuration, septicemia ("blood-poisoning "), and tetanus were of frequent occurrence and the mortality from certain surgical operations which are now almost free

from risk was often excessive. These facts are well known to the public and it is also generally known that when a wound made by the surgeon, or the result of accident, suppurates or gives rise to fever, it is because it has become infected. The germs which usually give rise to wound infection have been carefully studied by bacteriologists and are now well known. The two most common species, which are responsible to a large extent for the suppuration of wounds, for erysipelatous inflammation, and for "bloodpoisoning," are widely distributed and are commonly found upon the surface of the body and of mucous membranes in healthy persons. One of these is a micrococcus which, when cultivated in artificial media, is recognised by the fact that it forms masses of a golden-yellow colour. These masses are made up of minute spherical cells which adhere to each other in irregular grape-like bunches-hence the technical name Staphylococcus pyogenes aureus. The other is

also a micrococcus in which the spherical cells are united in chains, like strings of pearls. This is called Streptococcus pyogenes. This latter is also called the streptococcus of erysipelas because it has been demonstrated to be the cause of erysipelatous inflammations. These two species of pathogenic bacteria give rise to a great variety of infectious processes. Both are

found, either separately or associated, in the pus of

abscesses, in boils and carbuncles, in suppurating wounds, in puerperal fever, in peritonitis, in suppurative disease of the ear, in general blood-poisoning,

etc.

As in other infectious diseases infection by these pathogenic micrococci (so-called "pus cocci ") depends upon three factors, viz.: the virulence of the germ;

FIG. 10.

Micrococcus of pus-formation (Staphylococcus pyogenes aureus); magnified 1000 diameters.

the vital resistance of the tissues invaded; and the number of germs introduced into an open wound. The virulence of the germs is much greater when they come from a suppurating wound, from a case of erysipelas or of puerperal fever, or, in short, from any infectious process in the body, than when they come from the mouth or the surface of the body where they

have been living a saprophytic existence. Here it may be necessary to explain that a saprophytic bacterium is one which exists independently of a living host and which obtains its supply of nutriment from dead animal or vegetable material, while a parasitic bacterium is one which invades the body of a living animal and receives its nourishment at the expense

of

Micrococcus of erysipelas, etc. (Streptococcus pyogenes); magnified

FIG. II. 1000 diameters.

the tissues and body fluids of its "host." But certain bacteria, like those at present under consideration, may live either as saprophytes or as parasites.

Their ability to effect a lodgment in the tissues and multiply there, after having led a saprophytic life for some time, is favoured by a reduction in the vital resisting power of the individual as a result of various