216 



Bernard N. Jaroslow and Henry Quastler 

 Table I. Precipitin Reactions in the Agar Diffusion Test* 



* Each figure signifies the number of visible precipitin reactions in each test. 



VI. CONCLUSION 



The estimate obtained from our preliminary test is extremely crude; how- 

 ever, it agrees fairly well with the earher (1953) estimate. The number of 

 homologous reactions we observed was surprisingly low. We expect that 

 with more potent antisera it would increase markedly. If the observed 

 reactions are found to be cross reactions, or if repetition of the test with another 

 set of antigens gives fewer heterologous reactions, the value for TV would go 

 up radically. Also heterophile reactions will have to be differentiated from 

 each other to prevent a common heterophile such as the Forssman antigen 

 or the Wasserman cardiolipid antigen from lowering the value for A'^ by multiple 

 appearances in the tests. On the other hand, the similarity with Quastler's 

 estimate suggests that the order of magnitude of TV after further experimentation 

 will not be much greater. 



The preliminary tests were made with antigen complexes. It is known 

 that simultaneous immunization with many antigens does not produce sera 

 of optimum potency. In later tests, it might be worthwhile to try to isolate 

 antigens which show cross reaction or heterophilia, and use them to produce 

 more potent antisera. 



In the final analysis, we hope to obtain an estimate of the number of factors 

 or signals that are needed to characterize an antigen as to its specificity. 



REFERENCES 



1. H. Quastler: The specificity of elementary biological functions. In: Information Theory 

 in Biology, ed. by H. Quastler, 177-181, University of Illinois Press, Urbana (1953). 



2. J. Oudin: Methode d'analyse immunochimique par precipitation specifique en milieu 

 gelifie. C.R. Acad. Sci., Paris 111, 115-116 (1946). 



3. W. C. Boyd: Fundamentals of Immunology, 2nd ed., p. 91. Interscience, New York 

 (1948). 



4. W. Feller: An Introduction to Probability Theory and its Applications, vol. 1, p. 37, 

 J. Wiley and Sons, New York (1950). 



