VIII. VIRUSES AND INSECTS 183 



Such a phenomenon may never be confmed to insects or plants 

 only. Human beings may not be exceptional. It may be possible that 

 children inherit the structure of a virus from parent through the 

 germ cell, but that as the structure is transmitted in an altered form 

 the reversion of the complete virus form requires some periods after 

 the birth of the children, so that the virus appears when the children 

 grow up to some extent. The virus of measles may be one of the 

 viruses which can raise, in human protoplasm structure, a change 

 strong enough to be transmitted to progeny. Children who have 

 inherited the structure of measles virus from the parent may suffer 

 from measles, without the infection from outside, when the structure 

 recovers its complete form. 



In this connection it should be mentioned that bacteria infected 

 with phage may become lysogenic in which, however, the presence of 

 the virus cannot be demonstrated, but the bacteria are bound to 

 undei'go lysis with the liberation of the virus if brought under pecu- 

 liar environmental conditions (7). This fact must depend upon the 

 presence of the virus structure in an altered, inactive form in the 

 bacteria just as the structure of the measles virus may be in the germ 

 cells or in the premature children. 



In Chapter III in this Part is shown the fact that the seasonal 

 change in the morbility of measles strikingly resembles the change 

 in human conceptibility. Now, the writer is in the position to eluci- 

 date this phenomen clearly. Thus, the seasonal change in the human 

 conceptibility may be represented in a smooth curve presumably be- 

 cause of a regular seasonal change in the activity of hormonal glands, 

 while, on the other hand, the complete structure of measles virus m.ay 

 be developed in human cells just as hormones are excreted under the 

 regular influence of seasons. It may be said, therefore, that the re- 

 version of the virus structure tends to occur in a definite season when 

 the children grow up to a certain age. 



If the pattern of the structure of measles virus inherited from 

 parent is developed in a child, the pattern will be engraved in the 

 mother-germ cells of the child by the infection, and therefore the 

 pattern will be transmitted from generation to generation. If, however, 

 the normal structure of the protoplasm is sufficiently strong to reject 

 the virus structure, or at least powerful enough to overcome the virus 

 structure before it can engrave its pattern into the germ cell, the virus 

 will not be transmitted to the offspring. 



As is generally recognized, about 5 per cent of man do not suffer 

 from measles throughout life, showing that some persons possess a 

 strong predisposition to reject the virus. Even if the virus can afford 

 to affect such a person of strong predisposition, the structure of the 



