254 IV. THE PRINCIPLES OF LIFE PHENOMENA 



and microsomes appear to behave as assimilase and accordingly as 

 viruses owing to their rigid polymerization resulting from the high 

 content of nucleic acid, while at the same time they are known to 

 have various enzymatic actions. For example, it has been noted that 

 almost all the lactose activity in rat kidney homogenates can be sedi- 

 mented with microsome fraction. Mitochondrial fraction, on the other 

 hand, has been reported to have the major portion of the activity 

 of a number of tissue enzymes (50) (51). It has already been stated 

 that the structural pattern of these cytoplasmic particles is directed 

 by genes, and hence their enzymatic actions must also be governed 

 by the genes. 



Since viruses can be regarded as pathogenic genes, which determine 

 the pattern of the host cells after the infection, the enzymatic action 

 of the cells may likewise be changed according to the kind of viruses. 

 It has been found by Bauer (52) that chick eggs inoculated with 

 yellow fever virus showed a marked rise in xanthine oxidase acti- 

 vity of embryo and of chorio-allantoic tissues. Both virus titer and 

 enzyme activity reached a peak at about the 13 th day and then de- 

 creased. This may be a result of the change in the protoplasm 

 pattern raised by the abnormal gene, namely, yellow fever virus, 

 which may produce in the protoplasm protein the structure capable of 

 acting as xanthine oxidase. Fredericq and Gratia (53) have described 

 the phenomenon of stimulation of lactose fermentation by lactose- 

 negative bacteria submitted to the action of a certain type of phage, 

 a phenomenon indicating the production of the enzyme on the struc- 

 tural change by phage. 



Further, Kun and Smith (54) investigating the respiration of the 

 allantoic membrane infected with myxoma virus, found that zymo- 

 hexase activity was increased and lactic acid production was cor- 

 respondingly increased. On the contrary, if a virus pattern is incom- 

 patible with the pattern of some normally existing enzyme, the enzyme 

 will be destroyed by the virus infection. According to Bauer (55) 

 cholinesterase activity in mouse brain infected with yellow fever virus 

 falls gradually during the incubation period and reaches a minimum 

 value at the time when symptoms of encephalitis appear. 



Paramecia affected by kappa, as already stated, produce paramecin, 

 which can kill other paramecia having no kappa. This killing sub- 

 stance, paramecin, can likewise be considered as an enzyme directed 

 by a gene or a virus named kappa. Since paramecin may be the pro- 

 tein of the protozoa endowed with the pattern of kappa, it will strive 

 to give the pattern to normal paramecia, but paramecin itself cannot 

 multiply probably because of its failure of producing its exact replica, 

 although it can cause disturbance great enough to kill the protozoa. 



