338 V. THE NATURE OF EVOLUTION 



because of the likeness of the virus structure to the normal structure 

 of the protoplasm and because of the concealment of virus structure in 

 the protoplasm, not existing as an utterly independent entity. This 

 may also hold for bacteria ; namely, chemotherapy may be ineffective 

 against bacterial pattern which is present in the protoplasm in a latent 

 state or in a state not yet developed into their full pattern. For in- 

 stance, Chloromycetin, according to our observation, can for a period 

 of time expel dysentery bacteria from the carrier but the bacteria be- 

 come soon demonstrable in the feces, indicating that the antibio'tic is 

 ineffective to the undeveloped pattern of the bacteria. Streptomycin 

 may likewise be effective only to the tubercle bacilli having the com- 

 pletely developed pattern, so that the secondary infection by the bac- 

 teria themselves may be well effected by the drug, but with the in- 

 complete pattern or the latent bacteria in the tissues from which the 

 bacteria are being produced it may be powerless. 



An accomplishment of radical therapy by physical or chemical 

 agents, however, may not be impossible if it is attempted from the 

 view point of the reversibility above suggested. Red-ray therapy is 

 an old practice for small-pox, that is, red-ray exhibits beneficial effect 

 upon the disease which will be cured readily if the patient is exposed 

 to red-light. This should be comparable to the fact that bacteria or 

 phages damaged by ultraviolet-ray are activated by visible rays with 

 the recovery of the original structure. Similarly, tobacco-mosaic is 

 known to be cured by the exposure to red or blue light, whereas some 

 other plant virus diseases are said to be intensified by the visible 

 ray (9). 



Chemical agents may also be efficacious in this respect. The 

 agents must have hormone-like action in order to expel the unfavour- 

 able structures. It has been found by Wright (10) that coli bacteria 

 which underwent a mutation can recover their original character in 

 the presence of certain organic acids having a particular configuration. 

 Tartaric acid has this particular configuration and therefore proves 

 to be effective, but it should be noted that only natural D-form is 

 active, the L-form being inactive, suggesting its hormone-like action. 



Again according to Harare et al. (11) benzaldehyde thiosemicar- 

 bazone reduced the fatality rate of mice inoculated intranasally with 

 vaccinia virus. This chemical agent does not appear to inactivate the 

 virus as a result of prolonged contact in vitro. Derivatives with sub- 

 stitutions in the para-position of the benzene nucleus or in the 4-posi- 

 tion of the thiosemicarbazone molecule produce little or no protection 

 against vaccinia infection in mice (12). The =N— NH— CS— NHo group, 

 as such, appears to be essential for antivaccinal activity (13). Acker- 

 mann (14) found that administration of sodium fluoroacetate to mice 



