410 HARPER— ORGANIZATION, REPRODUCTION 



We have two sets of points of intersection between the walls of 

 the cells of series II. and series III., due to the fact that there are 

 ten cells in series III. to five cells in series II. We may consider 

 first the included angles of cells 2-6 about the five points of inter- 

 section marked ee^e-, etc. The values of these angles for the seven 

 colonies and their averages are given in Table IV. Point e is on 

 the axis. The remaining four points, e'^e'^, are placed symmetrically- 

 right and left of the axis mn as is indicated by their position in the 

 table. The average values of the lateral angles of cells 2, 3, 4, 5, 

 and 6 about these points e, e^, etc., are arranged in five corresponding 

 right and left pairs in Table V., section 3. 



There is no adequate evidence of any regularly progressive 

 change in value in the averages of these five pairs as compared with 

 the progressive change in value of the basal angles of these cells. 

 This is doubtless owing to the increased distance of these angles 

 from the five-sided central cell with its unequal included angles, due 

 to its inherited form tendencies. There is a manifest tendency for 

 the angles of intersection of the cell walls to become equal in har- 

 mony with the general symmetry of a least-surface configuration. 

 The values of these angles from the averages of the series agree 

 fairly well with the values of the corresponding angles in the selected 

 type figure. In the case of the lateral angles of cell 4, an arbitrary 

 value, 120°, was assigned in' the diagram. The actual average value 

 of these angles in colony 55 was 112°, as shown in the table ('16, 

 p. 98), and this is only two degrees from the average value of these 

 angles in the series of seven colonies. 



The values of the right and left pairs of the apical' angles of 

 cells 2-6 are given in Table V., section 4. There is considerable 

 fluctuation in the values of these angles but the average of the 

 series, 108°, agrees closely with the value obtained for the same 

 angles in the selected colony 55. In this case again an arbitrary 

 value (100°) was given to the apical angles of cell 4 in the type 

 diagram and the average for the series agrees with the measure- 

 ments from the selected colony, 109°, and not with the arbitrarily 

 assigned value. 



There is no clear evidence from the series that there is any pro- 

 gressive change in value of these apical angles odp, o'^d^p'^ of the 



