Heredity in Protozoa 629 



the inherited structure visibly appearing is not transmitted, some- 

 thing-is transmitted, namely, the condition of the protoplasm 

 which causes the production of the visible inherited structure. If 

 this determining condition were not transmitted, the visible 

 structure could not be produced in each generation. It is this 

 "something" transmitted that lies at the basis of the figurative 

 expression "bearer of heredity," or the like. 



12 What sort of modifications will remain permanently and be 

 transmitted to the progeny .? Evidently, only such modifications 

 as are not removed by the regulatory processes of the cell. The 

 modifications that are removed by regulation are precisely those 

 which interfere in one way or another with the physiological proc- 

 esses of the organism, while modifications which arise in harmony 

 with, or as a result of, the normal functioning of the cell are not 

 removed by regulation. Thus only characteristics of the latter 

 class — namely, adaptive characteristics— will be retained and 

 transmitted. Furthermore, it appears clear that the successive 

 modifications in the reproductive processes induced by these 

 adaptive characteristics must likewise be in harmony with the 

 normal functioning of the cell, else they would be removed by the 

 known regulatory activities of the cell. Thus all stages in the 

 modification, including the final one, must be in harmonious 

 adjustment to the normal activities of the organism. It would 

 appear therefore that only the new characteristics that are adaptive 

 will be inherited. Anything not in harmony with the normal func- 

 tioning of the cell will be removed by regulation. 



13 Let us now examine the problem of the "inheritance of 

 acquired characters. " What processes would be required for the 

 inheritance by the progeny of the same characteristic that has 

 already been produced directly in the parent, by environmental 

 action 1 



Keeping the Protozoa in mind, we have evidently two cases 

 here: 



a If the "acquired character" is some general chemical or 

 structural change in the parent cell — something that affects the 

 cell as a whole — then there appears to be no special difficulty in 

 the way of a direct transmission of this to the progeny, provided 



