238 IV. THE PRINCIPLES OF LIFE PHENOMENA 



are different from either of the infection viruses, having peculiarities 

 of both strains. In the example found by Delbruck and Bailey (16), 

 the new types are such as T2r and T4r+. 



Similar phenomenon has been likewise observed by Burnet and 

 Edney (17) with influenza viruses. From mixed infections in mouse 

 brain of the neurotropic influenza strain NWS and the non-neurotropic 

 strain MEL, virus strains which differ sharply from either of the 

 originals have been obtained. 



This phenomenon can be readily explained by the assumption 

 that the strong structure is restricted to a portion of the protein 

 molecules. If nucleic acid was inserted in a portion of the polymeri- 

 zation product of the thread-like protein molecules, only the portion 

 would have the strong structure, although it is well conceivable that 

 some portion of the protein threads themselves can possess the strong 

 structure. At any rate, if two particles, one of which has the strong 

 structure at portion A and the other at portion B, affect simultane- 

 ously a single protoplasm, portion A of the protoplasm protein will be 

 changed by the former and portion B by the latter independently 

 from each other. If the portions in which the structural patterns of 

 the two viruses are to be impressed are either identical or present 

 very near, the interference phenomenon may occur, whereas if the 

 portions are separated enough both patterns will be replicated with- 

 out interference. 



The formation of a replica of a strong structural pattern at a 

 certain portion of the protoplasm protein may lead in the organisms 

 to the appearance of property, which is determined by the structural 

 pattern of the portion regardless of the kind of replica of the other 

 portions. Namely, the particle having a strong structure at portion 

 A will give rise to the property determined by the structure at portion 

 A, and the particle having a strong structure at portion B will reveal 

 the property determined by the structure at portion B, and thus the 

 new progeny having the peculiarities of both particles will be gene- 

 rated. In such a case the particles will be regarded as genes capable 

 of determining the character peculiar to each particle. The mecha- 

 nism for causing localized changes in limited portions of the i!>rotoplasm 

 protein is apparently most advanced in the structure of genes of the 

 present-day higher organisms. 



2. The Structure of Genes 



As the organisms advanced the higher, their character would 

 become the more complicated, and at the same time the various loca- 



