310 ILLINOIS ACADEMY OF SCIENCE 
minus ) in two isolations, each being used as a check against the 
other, it was found that fluctuations were simultaneous in both 
isolations, and in the same directions, being thus independent 
of the effects of selection.” As additional data on the effects 
of selection, the parent-progeny correlation table is here given. 
TABLE III. 
PARENT-PROGENY CORRELATION TABLE WITH RESPECT TO BODY LENGTH IN TWO 
SUBLINES IN WHICH PLUS AND MINUS SELECTIONS WERE MADE. 
ZISISISIZ| SIF 
Fl bed br pd bed bb 
HiClOo1}Oo/|So colo 
BION | Ho o1o 
Progeny Alalaidin| ala 
1,00-1.19 
1.20-1.39 | 3) 3] 3] sae 
1.40-1.59 , oh aheliel ai ier 
1.60-1.79 | 2] 1| 7| 7] 6] [20] 
1.80-1.99 | | | 5] 3] 6] 5]19] 
2.00-2.19 | 2 2 
2] 6[2t/13[16] 5 [63] 
In this table we see a marked correlation between parents 
and progeny. The highest progeny mode is 1.80-1.99 mm. 
which was reached by the parent class having the greatest 
length, The lowest progeny mode 1.20-1.39 mm. is by the 
parent class having next to the shortest body length. The 
other progeny modes fall in the 1.60-1.79 group. Thus a 
considerable correlation is shown. 
When we run two check strains, keeping both under as nearly 
identical conditions as possible, and selecting in one in a plus 
direction and in the other in a minus direction, we have one 
of the best tests known for the effectiveness of selection. This 
was done in the case of the two sublines in question. It was 
impossible to separate the two sublines into strains differing 
genetically in regard to size. The correlation shown in the 
table presented, Table III, was equally evident in the plotted 
curves which were given (Ewing 1916, p. 64) for the results 
of selection in isolations No. 5 and No. 6; but more evident 
than this was the fact already mentioned, 7.e., that the fluctu- 
ations in the two sublines went together, and that the two could 
not be separated genetically in regard to body length. 
An Analytical Study of Variation and Regression in All 
Sublines where Selections were Made for Increasing Body 
Length. 
