394 PATHOGENIC MICROORGANISMS 



wash the red blood corpuscles used for the experiments, since many 

 animals normally possess small quantities of antihemolysin in their 

 blood-sera (man and horse especially). 26 The red blood corpuscles of 

 rabbits, dogs, and guinea-pigs are extremely susceptible to the action 

 of the staphylo-hemolysin. Those of man are less easily injured by it. 

 The hemolytic action takes place, as Todd 27 and others 28 have shown, 

 not only in vitro, but in the living animal as well. 



The staphylo-hemolysin is comparatively thermolabile. According 

 to Neisser and Wechsberg, heating it to 56 C. for twenty minutes 

 destroys it. According to some other authors, however, higher tem- 

 peratures (60 to 80 C.) are required. Reactivation of a destroyed 

 staphylo-hemolysin has so far been unsuccessful. The fact that anti- 

 staphylolysin is occasionally present in normal sera has been men- 

 tioned above. This antibody is most abundant in the blood of horses 

 and of man. Artificially antistaphylolysin formation is easily induced 

 by subcutaneous inoculation of staphylolysin into rabbits. 



Leucocidin. In 1894, Van de Velde 29 discovered that the pleural 

 exudate of rabbits following the injection of virulent staphylococci, 

 showed marked evidences of leucocyte destruction. He was subse- 

 quently able to show that the substance causing the death and partial 

 solution of the leucocytes was a soluble toxin formed by the staphylo- 

 coccus, not only in vivo, but in vitro as well ; for cultures of Staphylo- 

 coccus pyogenes aureus, grown in mixtures of bouillon and blood 

 serum, contained, within forty-eight hours, marked quantities of this 

 ' ' leucocidin. ' ' 



Other workers since Van de Velde have evolved various methods 

 for obtaining potent leucocidin. Bail 30 obtained it by growing virulent 

 staphylococcus in mixtures of one-per-cent glycerin solutions and rab- 

 bit serum. Neisser and Wechsberg 31 advise the use of a carefully 

 titrated alkalin bouillon. To obtain the leucocidin free from bacteria, 

 the cultures are passed through Chamberland or Berkefeld filters, 

 after about eight to eleven days' growth at 37 C., at which time the 

 contents in leucocidin are usually at their highest point. 



The action of leucocidin upon leucocytes may be observed in vivo 



26 Neisser, Deut. med. Woch., 1900. 



27 Todd, Trans. London Path. Soc., 1902. 

 2s Kraus, Wien. klin. Woch., 1902. 



29 Van de Velde, La Cellule, x, 1894. 



80 Bail, Arch. f. Hyg., xxxii, 1898. 



31 Neisser und Wechsberg, Zeit. f. Hyg., xxxvi, 1901. 



