I 4 o THE PRINCIPLES OF IMMUNOLOGY 



The action on the cells is independent of complement, there is no com- 

 bination at o C, but at 6 C. combination occurs, leading to hemolysis 

 only at higher temperatures. It, therefore, seems likely that these 

 bodies are similar to /toxins with a special affinity for erythrocytes. 

 The most favorable medium for developing these hemotoxins is broth, 

 but individual organisms require special conditions in the broth for 

 maximal production of hemotoxin. The development of the toxin fol- 

 lows fairly definite curves for the different organisms. For example, 

 staphylolysin begins to appear on the third day, reaches a peak on the 

 fifth day, drops on the sixth day, rises again on the eighth day, drops 

 again and reaches a final maximum on the thirteenth day. Megatheri- 

 olysin reaches a maximum on the seventh day and almost disappears 

 by the fifteenth day. De Kruif has recently shown that streptolysin 

 reaches its maximum in a few hours and has almost disappeared by 

 the end of twenty-four hours. The action is variable for different 

 species of corpuscles; staphylolysin acts powerfully on horse, sheep 

 and other bloods but only slightly on human and goat blood, whereas 

 megatheriolysin acts powerfully on human blood but not at all on horse 

 'blood. Nakayama has studied the streptolysin and finds that it is 

 filterable. He also passed the organisms through two species of 

 animals and finds that after animal passage the streptolysin is more 

 actively lytic for the corpuscles of the species which last harbored the 

 organisms. Streptolysin unites with the corpuscles in the course of 

 hemolysis, but the filtrate, after absorption of lysin, remains toxic for 

 mice. Many of the bacterial hemotoxins are thermolabile, being de- 

 stroyed at 60 to 65 C., but others are resistant to temperatures as 

 high as 1 00 C. The bacterial hemotoxins are active in vivo as well 

 as in vitro and are capable of producing severe anemias and even 

 death. An intravenous dose of 2.0 c.c. of a ten-day-old filtered broth 

 culture of staphylococcus produces in the rabbit marked reduction in 

 hemoglobin and the number of erythrocytes and may cause death in 

 six or seven days. It is probable that the secondary anemias which 

 often follow attacks of acute infectious disease may be dependent upon 

 bacterial hemotoxins. Ford, Lawrence and Williams have found that 

 cultivation of the bacillus Welchii in milk leads to the formation of 

 bacterial hemolysins, thus disproving the opinion previously held 

 that the hemolysis in gas bacillus infection was due to the formation 

 of lactic or butyric acid. The hemolysin described by Ford and Law- 

 rence is relatively stabile, not being destroyed until a temperature of 

 62 or 63 C. has been reached. It has other characters of true toxin 

 in that it is digested by pepsin and hydrochloric acid as well as by 

 pancreatin. It is precipitated by ethyl alcohol. It is antigenic, and 

 these investigators found that they could, by immunization, produce an 

 anti-hemolysin or anti-hemotoxin in titers of i 1000, 1-1250. 



Vegetable Hemolysins. Among the hemolytic substances of 

 vegetable origin are to be included those already discussed as phyto- 

 toxins, namely ricin, abrin, crotin, robin, phallin. Crotin and phallin 

 are more markedly hemolytic than the others, which are rather hemag- 



