GENETICS: W. E. CASTLE 
257 
segregation in individual cases. Bone measurements are believed to be 
less affected by extraneous influences than the growth curves of indi- 
viduals. Consequently our inquiry as to evidences of segregation will 
be confined to them. Three different bone measurements have been 
studied for each full grown individual (age 13 months or over, in most 
cases). These are maximum skull-length, maximum skull- width, and 
femur length. The facts arrived at are contained in Tables 1-3. 
In the first part of Table 1 is shown the variation in skull-length of 
10 full grown Cutleri females and of 28 full grown race B females. 
Measurements were made with a caliper rule furnished with a vernier, 
Weight 
400 
<J RaceB. 
AqeinDmis 40 80 )20 160 200 240 280 320 360 400 
FIG. 4. GROWTH CURVES OF RACE B MALES AND OF THE MALE HYBRIDS BOTH Fi AND F2, 
PRODUCED BY A CROSS WITH THE AREQUIPA RACE. 
and are accurate within 0.1 mm., the possible observational error shown 
by repeated measurement. The measurements are classified in classes 
of 0.5 mm. range numbered in order of increasing size. The lowest 
class, that numbered 1, would include measurements 48.5-48.9 mm.; 
class 2 would include measurements 49.0-49.4, etc. The absolute meas- 
urements included within each class of the table may thus be readily 
calculated, if desired. They are omitted for simplicity. The Cutleri 
females measured range in skull-length from class 1 to class 10. The 
race B females range from class 11 to class 25. Thus the two races do 
not overlap in range. Race B begins where Cutleri leaves off. Their 
means are 6.6 mm. apart. 
