I. THE THEORY OF MEMORY 339 



infected intranasally with influenza virus inhibits the growth of this 

 virus in the lungs of the mice ; further he (15) discovered that three 

 a-aminosulfonic acids cause marked inhibition of multiplication of in- 

 fluenza virus in tissue of the embryonated egg. Again, it has been 

 reported that 2, 4-dinitrophenol inhibits completely the propagation of 

 influenza virus in cholioallantoic membrane (16). These reagents 

 showed no virucidal effect in vitro. 



As stated above, the so-called antibiotics may affect directly the 

 complete pattern of pathogens and accordingly their effectiveness seems 

 to be restricted. Shope (17) has shown recently, however, that a cer- 

 tain mould can produce an agent which may provide an unfavourable 

 condition against the production of a virus pattern. He has isolated 

 an antiviral substance from penicilUum funiculosum, which is effective 

 upon infection of mice with viruses such as SK encephalomyelitis 

 virus. He believes that the agent causes an inhibition or interruption 

 of multiplication of the virus presumably by interference with some 

 stage in the developmental cycle of the virus. 



However, not all the agents which prevent the virus-reproduction 

 can be regarded as being capable of specifically acting to inhibit the 

 development of a certain virus pattern. Some may non-specifically al- 

 ter the protoplasm structure to render it inadequate for the establish- 

 ment of the structural change due to some viruses. 



Mirick et al. (18) claimed that urethane, given paraentrally or oral- 

 ly to mice, increased the severity of the infection with pneumonia 

 virus of mice. Not only were the lesions more extensive but mice 

 could be infected with smaller inocula of virus and the multiplication 

 of virus in the lung was enhanced. It should be naturally expected 

 that certain reagents are able to inhibit the development of a virus 

 pattern, while others promote it as in this example. 



2. Training Effect and the Oblivion of Memory 



The reversibility of protein appears to be especially manifest in 

 the protoplasm. Meanwhile, it should be noted that in the protoplasm 

 the reversible change from the normal to a certain other structure 

 appears to be facilitated by the repetition of the change. The so- 

 called anamnestic reaction (anamnesis = recollection) may be cited as an 

 example of this phenomenon. This reaction consists in that an animal, 

 which previously produced antibody in response to a specific antigenic 

 substance, will begin anew to produce the antibody vigorously when 

 a minute quantity of the antigenic substance is injected. For the 

 establishment of the reaction the repeated preliminary injection of the 



