84 INFECTION AND RESISTANCE 



ring, 17 and the "Osmotic Theory" of Baumgarten. 18 In the former 

 an attempt was made to demonstrate a parallelism between blood alka- 

 linity and bactericidal action the latter was based on the supposi- 

 tion that the destruction of bacteria in the body was largely due to 

 harmful osmotic conditions. Neither of these theories was long 

 seriously maintained. Behring himself took an active part in the 

 subsequent development of our present views. Baumgarten 19 still 

 clings to his own opinion in a modified way, in that he maintains 

 that the only effect produced by specific antibodies upon cells bac- 

 terial or otherwise is that they change the permeability of the cell 

 membranes and render them more vulnerable to osmotic injury. 



However crude or vague these theories may seem to us now, it 

 must not be forgotten that they were conceived at a time when no 

 knowledge had been gained regarding specific "antibodies." The 

 phagocytic powers to which Metchnikoff attributed natural immunity 

 and the bactericidal powers of the blood, regarded in the same light 

 by the Fliigge school, were general properties possessed by many 

 animals toward many different micro-organisms. That immuniza- 

 tion could specifically increase these functions toward the particular 

 micro-organisms used for treatment seemed indicated by the experi- 

 ments of Nuttall in which higher bactericidal power was found in 

 the blood of anthrax-immune calves than in that of normal animals. 

 However, no definite and conclusive work on the specific increase of 

 measurable serum or cell properties was available. 



This great advance, giving new energy and pointing out new 

 paths of investigation, came in 1890-1892 with the publication of the 

 work of Behring and his collaborators, Kitasato and Wernicke, on 

 immunity to diphtheria and tetanus. As we have indicated in a pre- 

 ceding paragraph, the fundamentally important points of this work 

 were as follows : 



1. The establishment of the fact that animals may be actively 

 immunized with products of bacterial metabolism true toxins or 

 exotoxins. 



2. The discovery that such active immunity was dependent upon 

 specific antibodies formed in the treated animal and circulating 

 freely in the blood ; and, 



3. That, by the transfer of the blood or the blood serum contain- 

 ing these specific antibodies other normal animals could be passively 

 protected not prophylactically only, but even after active disease 

 had set in. 



These observations were rapidly confirmed for tetanus by Tiz- 

 zoni and Cattani, and by Vaillard, and, similar but less successful 

 attempts at passive immunization were made in other diseases by 



17 v. Behring. CentralU. f. klin. Med., 1888, No. 38. 



18 Baumgarten. Berl. klin. Woch., 1899, 1900. 



19 Baumgarten. Lehrbuch, etc., 1912. 



