GENETICS: THE HERITABLE TRANSMISSION OF CATALYSTS 169 



lions of specific molecules included in the cytoplasms of sperm 

 and ovum. Many other kinds of specific atoms and molecules are 

 in most cases essential to full growth, development and reproduc- 

 tion, e.g., numerous vitamins and trace elements. These sub- 

 stances commonly serve as prosthetic or activating groups in essen- 

 tial biocatalysts which have a more or less limited functional 

 life and must therefore be continually renewed. 



What happens if strange and unusal atoms or molecules find 

 their way into the cytoplasm? While no unequivocal answer can 

 be given, in most cases where the invading substance is not 

 destroyed or utilized, it would probably be lethal. Certain con- 

 stituents of venoms or toxalbumins like ricin, abrin, botulinus 

 toxin, seem to function directly or indirectly as catalysts* and to 

 produce extensive chemical breakdown entirely out of proportion 

 to their small mass. It is certainly reasonable to expect that in 

 some cases stranger molecules may produce effects which are bene- 

 ficial, either by modifying existing catalysts or by serving to create 

 new ones. From the standpoint of genetics the important ques- 

 tion is: Can these new catalysts be carried on by heredity? Ex- 

 perimental evidence is accumulating to show that they can, thus 

 establishing a physicochemical basis for a mitigated form of 

 Lamarckism, which has been taboo in biological texts and teach- 

 ings because of lack of experimental evidence. 



Of particular interest here is the work on the ciliated protozoan 

 Paramecium aurelia by Professor T. M. Sonneborn of Indiana Uni- 

 versity, who was awarded the prize of the American Association for 

 the Advancement of Science on Jan. 1, 1947. One race of variety 4 of 

 this organism makes the fluid in which it lives poisonous for nearly 

 all other races of Paramecium, and is therefore known as a "killer"; 

 but it is resistant to its own poison. The "killer" character is deter- 

 mined by a four-component system: 



(1) a nuclear gene, K 



(2) an active product of this gene 



(3) a cytoplasmic unit, known as kappa 



(4) a final poisonous product or substance, called paramecin 

 The paramecin produced by one "killer" race may kill animals of 



another "killer" race; in one instance, two "killers" reciprocally killed 

 each other. At least one "non-killer" race was found resistant to the 

 paramecin produced by certain "killers"; but as a rule "non-killers" 

 are "sensitives" — that is, they are affected by the killer poison. 



Though no gene or genes can alone initiate the production of 



* Or catalyst inhibitors or "poisons". 



