164 IMMUNITY. THEORIES OF IMMUNITY 



Tissues Concerned in the Production of Antibodies. A large amount 

 of experimental work has been conducted in the study of the problem 

 of where in the body the antibodies are formed that develop in response 

 to immunization. The recent investigations of Hektoen and Curtis, 1 who 

 studied the effect on antibody production of the removal of various 

 organs, and of Hektoen 2 and Simonds and Jones, 8 on the influence of 

 exposure to z-rays, and of Simonds and Jones, 4 on the effect of injections 

 of benzol, indicate that the mechanisms concerned for the production 

 of antibodies are quite secure from certain disturbances and are princi- 

 pally located in the leukocytes and blood-forming organs, as the spleen, 

 lymphatic tissues, and bone-marrow. 



Specificity of Antibodies. Antibodies are usually specific for their 

 antigen, and it is upon this general law that the reactions of immunity are 

 based. It should be remembered, however, that not all antibodies are 

 protective; the agglutinins, for instance, apparently do not injure their 

 antigen. On the other hand, an animal may enjoy an immunity with- 

 out demonstrating the presence of any antibody in the body-fluids, and 

 another animal may show antibodies generally considered as possessing 

 protective powers, as, for example, the bacteriolysins, without neces- 

 sarily being immune. 



Upon what does the specificity of antibodies and immunologic 

 reactions depend? Specificity was at first believed to depend solely 

 upon some peculiar biologic relationship of the antigens, for it was found 

 comparatively easy to differentiate the serum of animals of dissimilar 

 nature by means of the precipitin and other reactions, and, as serum pro- 

 teins, which seemed to be quite similar chemically, but which were 

 obtained from unrelated species, were sharply differentiated by the 

 biologic reactions, it was considered that the specificity must be depend- 

 ent upon some principle quite apart from the ordinary chemical sub- 

 stances. 



With the use of proteins other than serums, and especially when more 

 or less purified proteins were employed, it has been quite firmly estab- 

 lished that specificity depends upon chemical composition, and that 

 differences in species, as exhibited by their biologic reactions, depend upon 

 distinct differences in the chemistry of their proteins (Wells). 



Pick and his coworkers have shown that two kinds of specificity 

 exist in each protein molecule: (1) One of these is easily changed by 

 various physical agents, such as heat, cold, and partial coagulation. 



1 Jour. Infect. Dis., 1915, 17, 409. 2 Jour. Infect. Dis., 1915, 17, 415. 



3 Jour. Med. Research, 1915, 33, 183. 4 Jour. Med. Research, 1915, 33, 197. 



