CELLS OF THE COLON BACILLUS 97 



gous to the physiological youth which has been demonstrated by 

 Child in multicellular tissues, as regenerating pieces of planarians. 

 It is noteworthy that Child also demonstrated this physiological 

 youth by increased susceptibility to injurious agents. 



These three correlated properties: Increased length and slender- 

 ness of the cells, indicating a greater magnitude of some axially 

 disposed force opposing the surface tension of the medium; increased 

 intensity of staining with basic dyes and decreased susceptibility to 

 acid agglutination, indicating an iso-electric point of the protoplasm 

 more on the acid side; and increased susceptibility to injurious 

 agents, all serve to distinguish the young, actively growing cells from 

 the resting cells, and justify our recognizing these long cells as a 

 distinct morphologic type, as embryonic cells, characteristic of the 

 growth phase of the culture. 



