THE STAPHYLOCOCCUS GROUP 291 
kept in the ice-box for twenty-four hours. The greatest dihition of 
broth showing hemolysis is considered the unit.^ This enzyme is 
destroyed or inactivated at a temperature of 60° C. in twenty minutes. 
Whether this hemolysin is identical with or produced parallel to the 
proteolytic enzyme of the staphylococcus has not been determined. 
Burckhardt^ believes the staphylolysin is a true hemolytic bacterial 
toxin; from his observations it appears to be non-protein in nature, not 
giving the biuret reaction. It is soluble in ether. Xeisser,'' and Xeisser 
and Wechsberg^ have prepared antihemotoxins to the hemotoxin of the 
staphylococcus by injecting subcutaneously increasing amounts of the 
latter into goats, beginning with small amounts (0.1 to 0.3 cc.) and 
repeating the injection three or four times. The antihemotoxin so 
obtained will neutralize the hemotoxin. 
Levkocidin.—\ Sin de Velde-^ has obtained an enzyme which destroys 
leukocytes by injecting virulent staphylococci into the pleural cavities 
of rabbits; the exudate, freed from cellular detritus by filtration through 
unglazed porcelain, rapidly kills and even dissolves fresh leukocytes. 
Xeisser and ^Yechsbe^g'^ were able to demonstrate a specific antileu- 
kocidin in the sera of rabbits inoculated with exudate containing leu- 
kocidin. Xeisser has shown that fresh leukocytes will reduce the color 
of dilute methylene blue solutions to the point of extinction; if dilute 
methylene blue is added to tubes containing leukocytes and leukocidin, 
no reduction occurs, thus indicating that the leukocytes are injured or 
destroyed. Leukocidin solutions alone fail to remove the color. 
Thrombokinase. —LoeWs observation^ that the products of growth 
of staphylococci cause blood to coagulate more rapidly than normal 
has been interpreted by ^Vluch^ to be due to a substance reacting like 
a thrombokinase. 
Distribution in Nature.— Staphylococci are found widely distributed 
in Xature, but associated rather closely with man and the higher 
domestic animals. These organisms do not appear to be adapted to 
a purely saprophytic existence. They are found in dust, particularly 
that of stables, houses and hospitals; they are common on the skin, 
the mucous membranes of the nose, mouth and to a lesser extent in 
the gastro-intestinal tract,'' the eye, the external ear and nearly always 
under the finger nails and in the hair follicles in man, which makes 
sterilization of the skin and hands difficult. 
Chemotaxis.— The bodies of staphylococci appear to contain sub- 
stances of unknown composition which attract leukocytes; the cell 
substance of killed cocci injected in the cornea frequently causes an 
1 It must be remembered that the sera of normal men and of animals frequently 
exhibit antihemolytie powers, hence the necessity of washing red blood cells thoroughly 
before testing the activity of staphylolysin upon them. 
= Arch. exp. Path. u. Pharm., 1910, 63, 107. 
3 Deutsch. med. Wchnschr., 1900, 26, 790. " Loc. cit. 
5 Ann. Inst. Pasteur, 1896, 10, 580. ' Ztschr. f. Hyg., 1901, 36, 299. 
■ Jour. Med. Res.. 1903, 10, 407. « Biochem. Ztschr., 1908, 14, 143. 
3 Moro: Jahrb. f. Kinderhelk., 1900, 52, 530. Streit: Inaug. Diss., Bonn, 1897. 
