404 V. THE NATURE OF EVOLUTION 



On this point the change raised by this principle is different from 

 mutation more than is the chang-e raised by usual viruses. 



This tendency is more manifest with the production of the so-called 

 adaptive enzymes. Adaptive enzymes may be produced as a result of 

 the adaptation of an organism to chemical substances whose specific 

 structure is transmitted to the genes of the organism. The production 

 of antibodies can be likewise regarded as a type of such adaptation 

 (71). In these cases, although the specific structure may be taransmit- 

 ted to the genes rather abruptly, the change can no more be called 

 mutation, since it is not only completely reversible but very useful to 

 the organism. 



Such a change is called adaptation because it is useful to the 

 organism, and such a usefulness has been undoubtedly established be- 

 cause the organisms capable of performing such a change could con- 

 tinue to exist, and therefore the character to adapt themselves to 

 chemical agents have been advanced amazingly in the organisms. In 

 this respect, it bears a striking resemblance to the gradual change due 

 to physical agents, both being purposeful and have been developed by 

 organisms for their existence. It should be realized that local changes 

 in somatic cells would never be transferred to the germ cells without 

 virus-like agents. This must be a very useful function of "virus", a 

 mutagenic agent. 



This seems the case not only with a single individual, but also with 

 an organized colony of gregarious animals such as termites and honey- 

 bees, as various individuals in such a colony may be regarded as so 

 many cells ; the colony may be equivalent to an individual of multicel- 

 lular organisms, and so the kings and queens may correspond to germ 

 cells, and workers and soldiers to somatic cells. 



The soldiers of termites have greatly enlarged mandibles, guard 

 the king and queen and defend the nest against the attacks of intruders. 

 Again, the specialized structures and habits of the workers of the 

 honeybees is remarkable, food is collected and stored, the young are 

 tended and fed. Each individual groups of these insects exhibit such 

 amazingly instinctive reactions, which must be the result of inherited 

 reflexes. How can have arisen and then inherited these characteristics 

 of each individual group, since the workers and soldiers leave no des- 

 cendant, unless the characteristics are transferred by virus-like agents 

 to the kings or queens ? 



Such a transmission of characteristics by virus-like agents appears 

 to occur even among fruit flies which are kept in laboratory. In an 

 observation with a certain strain of the fruit fly characterized by a 

 high mutation rate, Mampell (77) found that the mutability is increased 

 not only in this species but also in the individuals of another species 



