416 HARPER— ORGANIZATION, REPRODUCTION 



at these points. The central cell is more nearly isodiametric, etc. 

 In such a colony it is plain that the included angles of cell 6, and 

 those of all its immediate neighbors at least, are under quite dif- 

 ferent pressure relations than they would be with the normal cell 

 arrangement. Their fluctuations will be of a different order than if 

 they were normally placed. The writhing, struggling motions of 

 the final stage of swarming as described above could only have re- 

 sulted in the normal relations of equilibrium in case they had been of 

 sufficient violence to bring the cell out of its present abnormal rela- 

 tions into the normal so that the properly matched sides of it and its 

 neighbors would be in contact. 



The cell has reached a condition of equilibrium in its pressure 

 relations with the adjacent cells, but this equilibrium has not 

 achieved anything like equivalence in value or position for the cor- 

 responding sides and angles. The palpable asymmetry in this cell 

 6 and its neighbors is most convincing proof that the form of the 

 cell is not influenced merely by its pressure relations in the colony, 

 but also by its inherited tendency to assume the characteristic four- 

 lobed outline. The displacement of cell 6 is brought out very 

 clearly by comparing the right and left pair of cells 3 and 5 with 

 the right and left pair 2 and 6. In spite of fluctuating variations 

 cell 3 could be superimposed on cell 5 by merely rotating it on the 

 axis of the colony inn through an angle of 180°. Whereas to super- 

 impose cell 2 on cell 6 there would be necessary a further rotation 

 of No. 6 about its center and in the plane of the colony through 

 about 45° so as to bring the corresponding sides and angles of the 

 two cells together. 



Colony 6^ illustrates asymmetry originating in the displacement 

 of a single cell to the extent of bringing unmatched sides together. 

 This we may call anomogenous asymmetry as contrasted with the 

 asymmetries involving merely fluctuation in the values of sides and 

 angles without the passing of a critical point which alters the funda- 

 mental arrangement of the cells by bringing about abnormal juxta- 

 positions of sides and angles. 



All grades and degrees of this anomogenous displacement of 

 cells can be found in nature. Two general types of irregularity can 

 be distinguished. The first is an irregularity which does not pri- 



