Study of Bacterial Toxins 



55 



1 per cent. blood-Locke-mixtures, a very rapid decrease in the 

 rate of perfusion flow was noted. The coronary perfusion al- 

 most ceased by the end of five minutes. 



Histological sections of hearts thus perfused show an almost 

 total occlusion of the cardiac arterioles with agglutinated red 

 blood corpuscles. In most of our parallel test tube experiments, 

 recognizable hemagglutination did not take place. It is believed 

 that cardiac perfusion furnishes a more delicate index of hemag- 

 glutination than the ordinary test tube reaction 3 , and throws im- 

 portant light on the mechanism of streptococcus pathogenicity. 



3 Cardiotoxin of Streptococcus hemolyticus: In corpuscle- 

 free perfusions, streptococcus filtrates are markedly toxic for 

 the contractile and conducting tissues of the isolated rabbit 

 heart. The filtrates uniformly produce: (i) a marked loss of 

 myocardial tone, usually reaching a maximum within three 

 minutes, (ii) a temporary complete auricular-ventricular dis- 

 sociation (heart-block) usually lasting about five minutes, and 

 (iii) a progressively decreasing strength of the myocardial con- 

 tractions, usually leading to complete cessation of recordable 

 movements in from twelve to fifteen minutes. 



It is believed that these reactions throw light on the mechanism 

 of streptococcus toxicity, and give a valuable method for the 

 study of the immunological adaptations of cardian tissues. 



3 K. M. Howell, Jour. Infect. Dis., 1920, xxvii, 565. 



