AND INHERITANCE IN PEDIASTRUM. 407 



In Table V. I have brought together the average values of each 

 of the included angles of the cells arranged as right and left pairs 

 and the averages of these pairs in comparison with the correspond- 

 ing measurements of the selected colony No. 55 which I gave as noted 

 in a former paper ('16, pp. 98, 99). 



The table, section i, gives in order the values of each of the five 

 included angles of the centeral cell and of the included angles of 

 the cells of series II. and III. in these seven colonies arranged in 

 right and left pairs and averaged. In the right-hand column are 

 the corresponding values for the selected colony, No. 55. For con- 

 venience we may call the unpaired angle of the central cell, igi^, the 

 basal angle. The right and left pair of angles igH^ and i^gH^ the 

 lateral angles, and the remaining pair which measure the two lobes 

 of the cell ig~i^ and i*g^i^ the apical angles. In the cells of series 

 II. (except cell 4) we shall have two basal, two lateral and two 

 apical angles and in cell 4 and in all the cells of series III. three 

 basal angles, for example, in cell 12 p*d*r*, p''d^r^, and p*h^p^ and in 

 cell 4 the corresponding three angles. 



In the central cell the unpaired angle igi^ on the axis of the colony 

 is the largest of the five in both cases. It is 115° for the average of 

 the series and 111° for the single colony. The apical pair of angles 

 bounding the tips of the lobes i^g-i^ 90° and i*g^i^ 90° are the smallest 

 of the five. Their values are nearly equal in the averages from the 

 series, as they should be for the bilateral symmetry of the colony. 

 In the single colony, No. 55, they are markedly unequal, 81° and 

 93°, though their average, 87°, is only three degrees different from 

 the average of the series 90°. 



The average values of the lateral angles ig'^i^ 107° and ig'^i^ 105° 

 are intermediate between those of the basal and apical angles of the 

 cell in the averages of the series as they also are in the single colony. 

 In the latter again they differ by 11° though their average, 108°, 

 dift'ers by only 2° from that of the series, 106°. On the whole, 

 the differences between the typical shape of the central cell as de- 

 termined from the selected individual and as determined by the 

 average of a selected series are within the range of errors in meas- 

 urement by the methods used for angular dimensions in photographs 

 of such objects. 



