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Scientific Proceedings (104). 



division rate and number of divisions, but high in endurance. 

 The other series were intermediate as regards vitality some of 

 them being high in (1) and intermediate in (2) and (3) as in series 

 D, L, N, 0, and /. 



Without exception the series showing high vitality in all 

 three ways came from young parents. Thus the C series started 

 when the parent A series was 70 days old and in the 78th gener- 

 ation ; the F series started when the parent C series was 50 days old 

 and in the 86th generation; the I series was started when the 

 parent F series was 100 days old and in the 143d generation; the 

 P series and both U series came from the L series which was 70 

 days old and in the 11 6th generation when the P series started, 

 and 140 days, or twice as old, and in the 208th generation when 

 Ui and U2 were started; the V series, finally, was started from the 

 P series when the latter was 90 days and 120 generations old. 



Without exception, also, the series showing low vitality in all 

 three ways came from old parents. Thus the Q series was started 

 when the parent J series was 200 days old and in its 316th gener- 

 ation and should be contrasted with the L series which came from 

 the same parent when younger ; the R series was started when the 

 parent / series was 160 days old and in the 245th generation, and 

 should be contrasted with the N series which came from the same 

 parent when it was 120 days old and in the 188th generation; 

 the a series was started when the parent P series was 210 days old 

 and in the 291st generation and should be contrasted with the 

 V series which came from the same parents when they were 90 

 days old and in the 120th generation. The W series and the H 

 series both of which were weak in respect to division rate and 

 number of generations came from parents that were similarly old, 

 the W series from N when in its 225th generation; the H series 

 from A in its 237th generation. The J series was exceptional, for, 

 coming from very old parents (A series when 250 days old and in 

 the 311th generation) it was weak only in endurance. 



