478 



G. N. CALKINS AND L. H. GREGORY 



Similar variations in vitality are shown in the histories of series 



B, E', O and P, and of the 4-line series G, H', L, M, Q and T', 

 although the daily division rate has not been tested for these 

 other cases. Of the 14 pure lines of the B series, 3 only are left 

 from quadrant A, 1 from B, 5 from C and 4 from D, the greatest 

 mortality occurring in A and B. Of the 15 lines now living of 

 the E' series only 2 are in quadrant A, 4 are in quadrant B, 6 in 



C, and 3 in D. Again quadrant A is the weakest. In series O 



