100 IMMUNO-CATALYSIS 



in this respect in an "adopted" cell is merely a quantitative change 

 and, therefore, does not represent theoretical significence. 



d. Consideration of the Primary Role of Antigen in Antibody 

 Production as Postulated by Burnet, et al. Burnet, et al. postulate that 

 antigens taken into the antibody forming cells lastingly modify cellular 

 proteinase units which then synthesize antibodies specific to antigens. 

 The claimed lasting character and the inheritability from parent to 

 daughter cells of this modification implies, in the light of the present 

 concept of the role of genes in the synthesis of specific enzymes, that 

 antigens bring about an inheritable variation in the genes. This varia- 

 tion is not a degradative mutation but a building-up process since the 

 specific enzyme system not only is still capable of synthesizing the 

 total quota of normal but also the new species specifically related 

 antibody globulins. This assumption conflicts with the well established 

 genetic characteristics of species. 



Known facts instruct us that a cell may undergo the following three 

 types of genetic changes: 



(1) Chromosomal changes and gene mutations. Such directed 

 changes have not been demonstrated in antibody formation 

 against foreign proteins. 



(2) A building-up process which requires the incorporation and 

 inheritance of genetic factors acquired by a cross-fertilization 

 (Lindegren and Lindegren, 1945), or, in an asexual (?) cell 

 (e.g., bacteria), by the incorporation into the recipient reces- 

 sive cell of cytoplasmic material or of a catalyst of genetic 

 nature from another strain of higher order but of the same 

 species (Avery, et al. 1944). Recombinations might also re- 

 sult in degenerative changes depending on the nature of 

 recombining factors. 



(3) Degenerative mutations by which a cell undergoes hereditary 

 losses as the consequence of the action of toxic agents, as 

 observed in the development of resistance to drugs (Sevag, 

 1946). The hereditary cytoplasmic changes in the enzymatic 

 constitution of yeast (Ephrussi, et al., 1949; Slonimski and 

 Ephrussi, 1949) are clearly degenerative changes. The 

 changes in the antigenic types in 'Paramecium aurelia 

 (Sonneborn, 1949) may also be interpreted as degenerative 

 changes. In this case, every potentiation of an antigen re- 

 sults from or is associated with the suppression of another. 



