34 H. E. EWING. 



selected, each being a descendent of a different individual of F 7 

 generation. F 8 i gave offspring with a mean of 1.85:1, and 

 F 8 I9 offspring with a mean of 1.83:1. The former converged 

 slightly toward the mean base line of the original strain, the 

 latter reverted not only to it but beyond it, so that the means 

 of the two fraternities almost meet. From these fraternities 

 F 9 9, formula 2.08:1, and F 9 I7, formula 1.77:1, were taken, each 

 again being selected from the different pseudostrain. Although 

 the former had an antennal formula very high, 2.08:1, in fact 

 higher than that of any individual selected during the whole 

 experiment, yet its seven offspring gave the remarkably low 

 fraternal mean of 1.66:1. Thus reversion in this case was not 

 to the mean of the original strain but much beyond it, as has 

 been noted before in the case of selections from the Fe and Fg 

 generations. From F 9 i7, only a single individual was obtained 

 which gave a formula of 1.71 :i, a slight deviation from the mean 

 base line. 



CONCLUSIONS. 



The following conclusions can be drawn from the results 

 obtained. Selections from among extreme variants do not alter 

 the mean as obtained for the strain without selection. The 

 fraternal mean of any generation may show a great fluctuation 

 from the mean of the strain, but this fluctuation is not trans- 

 mitted to following generations. The offspring of an extreme 

 variant may show not a reversion to the mean of the line or 

 strain, but a reversion which swings pendulum-like much beyond 

 this mean, only to be brought back to its former side of the 

 mean-of-the-strain base line in the next generation. This 

 phenomenon I call oscillating reversion. Great deviations from 

 the mean of the strain occur among fraternities which have been 

 produced by individuals whose formula is almost the same as 

 that of the mean of the strain. This great divergence is due to 

 some underlying cause not yet determined, and is independent 

 of the nature or amount of food. 



