58 
R< search Bulletin No. 2 
( 60-3x54 )-6 1ES, (60-5x54) -2-3 AS, and (60-5x54) -12-2ES. with 
means of 4.9 ± .08, 4.8 ± .07, and 4.6 ± .04 respectively. These 
means do not approach the mean of the Tom Thumb race very 
closely, yet the appearance of the families. is ; as a whole, very 
like the Tom Thumb. Furthermore, the great difference in varia- 
bility among the F 3 families, extending as it does from 13.90 ± .67 
per cent to 24.96 ± 1.35 per cent, indicates a difference in hetero- 
zygosity from which we might well argue the ease of producing 
races like the original parental strains with a little more selection. 
The family (60-5x54) -11-2AS, coming from a large segregate 
of F 2 , gave a fraternity with a mean seed weight of 7.3 — .08 
grams. This is probably very close to the true mean seed weight 
of a. well-selected Black Mexican race. 
