74 Inside the Living Cell 



DNA molecule can exchange parts with another one, during the course 

 of the duplication process. Of course this may not be a simple 

 exchange of parts. It is quite likely that it occurs during the duphca- 

 tion of the nucleotide threads, in that the rephcation process which 

 is forming a new nucleic acid particle along one fibre, jumps to a 

 second one which happens to be in the vicinity. 



Another remarkable discovery is that bacteria can exchange 

 material carrying genie characteristics with each other. Plate 10, by 

 E. L. Wollman, F. Jacob, and W. Hayes of the Pasteur Institute, Paris, 

 shows two bacteria in conjunction. This is a kind of primitive sexual 

 process. A bridge is formed between the bacteria, through which genie 

 particles are exchanged. It has even been found possible to control 

 the number of genes which are transferred by stopping the conjunc- 

 tion (by agitation) after different times. But this conjunction is a rare 

 process affecting not more than one cell in a million — often even less 

 — at any one time. 



