144 TOXINES AND ANTITOXINES. 



The same species of staphylococci that produce the lysine also 

 produce leucocidine, although far from invariably in correspond- 

 ing quantity. As in the case of the lysine, passage through an 

 animal increases the production of poison. It is, nevertheless, 

 a specific poison unmistakably distinct from, the lysine^ and 

 possesses its own haptophore and toxophore groups. The lysine 

 does not combine with the leucocytes. Leucocidine passes into 

 the sterilised filtrates and is thus a soluble poison. 



It is somewhat less stable than the lysine. At 50 C. it is 

 destroyed in twenty minutes, and at 58 C. in ten minutes. 

 When kept, preserved with phenol, in an ice chest it very 

 rapidly becomes weaker, its activity being from twenty-five to 

 sixty times less after sixteen days. Eventually it becomes quite 

 inactive. 



Its action is fairly slow, so that it is essential to extend the 

 period of observation to two hours. It is shown to be a true 

 toxine by the fact that it is capable of forming an antitoxine. 

 DENYS and VAN DE VELDE x were the first to prepare an anti- 

 leucocidine by means of the injections of the filtrates from 

 cultivations. Then NEISSER and WECHSBERG discovered anti- 

 leucocidine in normal horse serum and human serum, but not in 

 that of the rabbit ; in like manner they invariably obtained an 

 antileucocidine of uniform character by immunising rabbits and 

 goats. 



We have thus in the leucocidine of staphylococci a true toxine, 

 which has specific action upon leucocytes characteristic activity 

 which has hitherto only had an analogy in the pneumococcus 

 leucocidine discovered by CASAGRANDI (loc. cit.). 



1 Denys and Van de Velde, " Sur la production d'une antileucocidine, 

 &c.," La Cellule, xi., quoted by Neisser and Wechsberg. 



