230 IV. THE PRINCIPLES OF LIFE PHENOMENA 



between two masses thus brought into contact, they would combine 

 with each othei" and the one with the stronger structure would over- 

 come and assimilize the other. This must have been a struggle for 

 existence, a struggle to eat or to be eaten. Thus the individuals 

 with the stronger assimilase action could survive and prosper the 

 more extensively. 



The strength of the structure might be determined chiefly by 

 both the arrangement and type of polar groups in the protein which 

 constituted the mass, but of the masses of the similar proteins, the 

 nucleic acid content might play an important part as in the case of 

 viruses. The masses therefore capable of getting possession of great 

 amounts af nucleic acids or nucleic acid-like substances would become 

 powerful in their assimilase action, and accordingly would become 

 more fitted for the continued existence. 



In this problem, however, there seems to be involved a great 

 dilemma. As stated in Part II, for the response to stimuli and for 

 the spread of the structural change produced by the stimuli, lipids 

 must be inserted among protein threads of the protoplasm, but in 

 such a state the assimilase action of the protoplasm is extremely 

 weak, and will be easily assimilized by other assimilases. On the 

 other hand, if nucleic acids are contained in rich amount, the struc- 

 ture will become rigid and exhibit a strong assimilase action, but in 

 this state, as a natural result, structural changes essential for life 

 phenomena will scarcely occur. Primeval organisms had to find their 

 way out of this dilemma in order to continue their existence, and did 

 actually find a splended way as discussed in the next chapter. 



