2 COLLECTED STUDIES IN IMMUNITY. 



chenschr., 1896, Nos. 7 and 8) and which is here reproduced only in 

 its main features. 



The immunizing substances contained in cholera serum possess 

 but feeble power to retard development. They are nothing but an 

 antecedent form of substances developed in the peritoneum of the 

 guinea-pig, specifically solvent for cholera vibrios. They are stored 

 in the animal body in an inactive but stable form, somewhat as 

 glycogen is stored in cell depots as an antecedent form of grape- 

 sugar. When needed, these inactive substances of the serum can be 

 converted into the specific active form through the active interference 

 of the body-cells. This conversion can also be effected by the addi- 

 tion of a suitable serum. In this added serum a certain "something/' 

 present in very small amounts, effects the change, but is very soon 

 used up in the process. In the animal body, on the other hand, 

 this constituent is produced by the body-cells as long as the stimulus, 

 caused by the presence of the cholera bacilli, lasts. The action of 

 this substance is ferment-like. Bacteriolysis is also regarded as a 

 ferment action, caused by ferments of a very peculiar kind. These 

 ferments are fitted in an absolutely specific manner each to a single 

 bacterial protoplasm, acting on this exactly as pepsin or trypsin acts 

 on coagulated albumin. According to Pfeiffer, a somewhat distant 

 analogy is seen in E. Fischer's yeast ferments, each of which can only 

 split up a sugar of a definite composition. If this theory be correct, 

 these specific ferments must exist in an active and an inactive modi- 

 fication. 



Recently Bordet (Annal. Inst. Pasteur, Vol. 12, No. 10) pub- 

 lished a series of experiments in which he showed that the laws which 

 govern the specific bacteriolytic action of immune sera govern also 

 certain specific solvent phenomena seen in red blood-cells. 



Bordet treated guinea-pigs with repeated injections of defibri- 

 nated rabbit blood. The serum of animals so treated possesses the 

 property of dissolving rabbit blood in vitro rapidly and with great 

 intensity, whereas serum of normal guinea-pigs is unable to do this. 

 Solution is preceded by a marked agglutination of the erythrocytes. 

 On heating the specific serum for half an hour to 55 C. the hsemolytic 

 power is destroyed, while the agglutinating power remains. The 

 serum thus inactivated can again be rendered active by the addition 

 of a certain amount of normal guinea-pig serum, and even of normal 

 rabbit serum. The active guinea-pig serum has no effect on the 

 red blood- cells of the guinea-pig itself or on those of pigeons, but 



