IMPLICATIONS OF CLONAL SELECTION 



related determinants. It may be that this evidence of in- 

 creased immunological reactivity with a new type of antigen, 

 never actually experienced as an antigenic stimulus, will be 

 of some value in convincing those with a firmly Lamarckian 

 attitude to antibody production of the potentialities of pre- 

 adaptation by ' chance ' mutation. 



To complete the type of experimental evidence having 

 some bearing on these questions, we may add the finding that 

 so far it has not been possible to show that a single globulin 

 molecule will react with two distinct and unrelated antigens 

 even when they are inoculated together, nor that a single 

 cell can produce an antibody population that will react in 

 this double fashion. 



If we attempt to pull together this rather fragmentary 

 evidence into a coherent interpretation, it may emerge in 

 the form of two general conclusions : 



(i) The clones ' produced ' as a result of a virus infection 

 are composed of cells which have active sites corres- 

 ponding to several of the antigenic determinants, 

 (ii) Active sites can be modified so that the globulin pro- 

 duced is capable of reacting with various modifications 

 of an antigenic determinant pattern. 

 If (i) is correct, it has a very important implication, 

 namely, that some means of transferring a genetic potentiality 

 from a cell of one clone to a cell of another must exist. Such 

 a capacity has always been recognized as something which 

 might be needed to account for aspects of antibody produc- 

 tion, though its use, for example in Burnet and Fenner 

 (1949), was in distinctly different fashion from what is being 

 suggested here. The working hypothesis would be that in the 

 lymph node to which influenza virus particles and various 

 antigenic fragments will be brought, clones with a b c and 

 d prototype sites will be stimulated to proliferate. Cells from 

 all will be in close mutual contact and replicating. Transfer 

 of a specific inheritable capacity from one to another could 

 be envisaged at either nuclear or cytoplasmic level. The only 



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