THE STAPHYLOCOCCUS GROUP 259 



both in vivo and in vitro. In vitro this enzyme, staphylolysin, appears 

 to digest the stroma of red blood cells, liberating hemoglobin from 

 them. A quantitative measure of the activity of this hemolysin can 

 be made by adding gradually decreasing amounts of broth culture 

 (filtered through unglazed porcelain) to well-washed red blood cells 

 suspended in salt solution; the mixtures are incubated at 37 C. 

 for one hour, then kept in the ice box twenty-four hours. The greatest 

 dilution of broth showing hemolysis is considered the unit. 1 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 2 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. 



Leucocidin. Van de Velde 3 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 leuko- 

 cytes. Neisser 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 leuko- 

 cidin, no reduction occurs, thus indicating that the leukocytes are in- 

 jured or destroyed. Leukocidin solutions alone fail to remove the color. 



Thrombokinase. Loeb's observation 4 that the products of growth 

 of staphylococci cause blood to coagulate more rapidly than normal 

 .has been interpreted by Much 5 to be due to a substance reacting like 

 a thrombokinase. 



Distribution in Nature. Staphylococci are found widely distributed 

 in nature, 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, 6 the eye, the external ear, and nearly always 



1 It must be remembered that the sera of normal men and of animals frequently 

 exhibit antibemolytic powers, hence the necessity of washing red blood cells thor- 

 oughly before testing the activity of staphylolysin upon them. 



2 Arch, exp: Path. u. Pharm., 1910, Ixiii, 107. 



3 Ann. Inst. Past., 1896. 



4 Jour. Med. Res., 1903, x, 407. 

 6 Biochem. Zeit., 1908, xiv, 143. 



6 Moro, Jahrb. f. Kinderheilk., lii, 530; Streit, Inaug. Diss., Bonn, 1897. 



