660 ACTIVE IMMUNIZATION 



plished by the production of antibodies so that they may be at hand to 

 overcome an infection if it should occur. For example, the antibodies 

 specific against the virus of smallpox may be produced by inoculation 

 with cowpox virus, so that for years the system will be protected against 

 smallpox. Even if vaccination has been delayed until smallpox has 

 actually been contracted, inoculation with cowpox virus early in the 

 period of incubation so stimulates the body-cells that sufficient anti- 

 bodies are produced to modify and lessen considerably the virulence 

 of the smallpox virus. 



This is especially true in rabies, when the vaccine is given in such 

 doses and at such intervals that sufficient antibodies are produced to 

 neutralize the effects of rabic virus and actually to destroy it during the 

 period of incubation or during the interval that elapses between the 

 time of infection and the appearance of the symptoms. In this way 

 the great majority of infected persons escape the sufferings of rabies 

 by enduring the relatively slight discomfort consequent to a series of 

 subcutaneous injections. 



(b) For the treatment of disease. This is the bacterin or vaccine 

 therapy, a method that owes its origin to the researches of Sir Almroth 

 Wright and his colleagues. It was originally employed in the treatment 

 of those infections that showed a tendency to chronicity in which true toxins 

 played little or no part. Since recovery from an infection is in general 

 dependent upon the mechanical removal of the infecting agent, aided 

 by antibodies that facilitate phagocytosis or directly destroy the invading 

 bacterium and neutralize its products, Wright believed that in chronic 

 infections autovaccination, or stimulation of the body-cells to the 

 production of antibodies, by reason of the fact that it is irregularly 

 timed, is generally insufficient or altogether absent. For these reasons 

 he believes that any stimulus that will arouse the body-cells to throwing 

 into the circulation substances from the invading bacterium or diseased 

 tissues, may result in increased antibody formation, followed eventually 

 by clinical improvement or cure. In certain cases this stimulation may 

 be secured by judicious massage or manipulation of the diseased part, 

 by passive hyperemia (Bier), or by similar procedures. 



However, if the microorganism is obtained and cultivated artificially, 

 it is possible, in many instances, so to modify or attenuate the bacilli 

 (usually by heat) that they may be reinjected into the patient in suffi- 

 cient numbers to furnish the stimulus necessary for arousing dormant 

 or uninvolved body-cells to produce the opsonins and other antibodies 

 necessary for overcoming the infection. In other words, with each in- 



