280 BACTERIOLOGY 



affinity is indirectly the cause of compensatory bioplastic 

 activity on tfie part of similar surrounding atom-groups 

 that have not been destroyed. This results, as we learned 

 above, in hypercompensation, the excess of plastic material 

 being disengaged from the parent-cell and thrown free into 

 the circulating fluids, there to combine directly with the 

 same intoxicant should it subsequently gain access to the 

 animal. This excess of plastic material thrown into the 

 circulation combines, according to Ehrlich,i directly with 

 the intoxicant to form physiologically inactive "toxin — 

 antitoxin" compounds, and can therefore be reasonably 

 regarded as the antitoxic material of animals rendered 

 immune from bacterial and other toxins. 



Since the announcement of that doctrine many important 

 advances have been made in our knowledge of the subject. 

 We have learned that the reactions of immunity or tolerance 

 may be induced by the use of other intoxicants than those 

 elaborated by bacteria, and by the employment of other 

 cells and cell secretions. It has been demonstrated that 

 antibodies, differing in their specific actions from anti- 

 toxins, but originating probably in a similar manner, are 

 to be detected in the fluids of animals thus immunized or 

 rendered tolerant. For a long time we have known of the 

 germicidal action of normal blood-serum; since 1895 we 

 have been familiar with the singular bacteriolytic phenome- 

 non demonstrated by Pfeiffer in the peritoneum of animals 

 immune from cholera; later we learned that the development 

 of immunity from a variety of infections is accompanied 

 by, a power on the part of the serum of the immune animal 

 to agglutinate the bacteria causing the infection; the work 



' Zur Kennitnisa der Antitoxinwirkiing, Fortschritte der Medicin, 1897, 

 Bd. XV, No. 2. 



