316 CAUCH LITELE 
ferent and shows a great increase in the percentage of observa- 
tions showing growth. Its percentage of 21.58+1.28 differs 
from the lower group by 7.81 +1.65 and is 4.6 times its probable 
error. f 
We have then to explain a decrease of percentage in observa- 
tions showing growth in the common stock (N) series in the 
higher age group as compared with the lower, and directly the 
opposite result in the (B.C.) series, where the higher age group 
shows a significant increase in percentage of observations showing 
growth. 
TABLE 6 
COMMON o's 
AGE 
1 = Jo + 
CoAT. SN Ss code 76 408 15.70+1.64 |) Diff. 5.40+2.03 
TSAO Fn. / pane 44 383 10.30+1.20 |f 2.6 X P.E. 
COMMON Q's 
331 19.46+1.31 |\ Diff. 10.7+1.51 
463 9.39+0.87 |f 7x Pan: 
1In this table and in table 7 certain recent experiments are included, the 
results of which became known after thé values of the previous tables had been 
calculated. Inasmuch as they merely confirm the previous findings and in- 
clude only very small numbers, it did not appear worth while to include them 
in the curves until another tabulation was made. 
We have seen that the distinctions between the higher and 
lower age groups exist when the sexes are lumped together. The 
next obvious step is to see whether a sex difference exists. Tables 
6 and 7 bear on this point. 
Table 6 shows the upper and lower age groups of males and 
females within the common (N) series. 
It will be seen that there is no significant difference in the total 
percentage of growth between males and females when all ages 
are lumped. In fact, the two percentages of 13.17 and 13.88, 
respectively, are close enough to be striking. The same holds 
in the case of males when the upper and lower age groups are 
