118 TSE SPECIFIC PRECIPITINS. 



2. There appears in the blood of the immunized animals an anti- 

 toxin which in vitro neutralizes the solvent action of the toxin on 

 the red blood corpuscles of the rabbit, and which, when injected into 

 the blood, prevents the action of the toxin. 



3. This antitoxin appears in the blood promptly, even after from 

 two to four injections, and in the rabbit it is at this time at its 

 maximum strength ; in general, its antitoxic value is not great. 



4. In the course of a prolonged immunization, the strength of the 

 antitoxin progressively diminishes while the resistance of the rabbit 

 against the toxin increases. 



5. The red blood corpuscles of immunized rabbits are less soluble 

 in the serum of the eel than are the corpuscles of non-treated 

 animals. 



6. The resistance of the corpuscles is not in proportion to the 

 amount of antitoxin present in the blood of the immunized animal ; 

 on the contrary, one observes a certain antagonism between the re- 

 sistance of the corpuscles and the strength of the antitoxin, and in 

 instances in which the latter is of relatively great strength the solu- 

 bility of the corpuscles may be slightly augmented. 



7. The injection of eel serum into the blood is followed by a nota- 

 ble diminution in the number of leucocytes in an untreated animal 

 and an augmentation or a slight diminution in immunized animals. 

 In a mixture of eel serum with an antitoxin obtained from an im- 

 munized animal one observes a cloudiness and a precipitation similar 

 to that reported by Kraus in filtered bacterial cultures. This pre- 

 cipitate is insoluble in water, in neutral salts, and in alkaline car- 

 bonates, but is easily soluble in alkalis and acids. Its formation 

 resembles the coagulation of a substance dissolved in toxic or anti- 

 toxic serum. 



8. The volume of this precipitate is ordinarily in proportion to 

 the strength of the antitoxin ; its formation is retarded by heating 

 the antitoxin to 70° for one-half hour ; and heating the eel serum to 

 80° renders it incoagulable by the antitoxin. 



9. The coagulation is not directly due to the antitoxin for one may 

 obtain antitoxic sera which do not give a coagulum. 



10. Antitoxic sera acquire very promptly the property of agglu- 

 tinating the red corpuscles of the animals whose blood or serum is 

 injected. 



11. The power of agglutinating the red blood corpuscles does not 

 correspond with the coagulating power and the former may be pro- 

 nounced in a serum which does not coagulate its homologous toxin. 



12. The agglutination of red blood corpuscles is not caused by the 

 coagulation of substances dissolved in the liquid portion. 



Bordet ^ injected the defibrinated blood of the chicken into rabbits 

 and obtained from the latter a serum which produced a precipitum 

 ^Aimale$ de FlmtUut Pcuteur, 13. 



