1912] HARRIS—STAPHYLEA S11 
obtained from the lumped samples or ‘‘population,’’ with the 
(unweighted) means of the constants for the several individuals. 
The means of the three characters are roughly the same for both 
methods. The standard deviations of both / and o show large 
differences. The S.D. is dependent upon the differences of the 
means of individuals as well as upon the variation among the pods 
of the same plant, hence the mean S.D. of the individuals is less 
than that for the combined sample. 
TABLE V 
COMPARISON OF CONSTANTS FOR GENERAL POPULATION WITH THE MEAN VALUES 
ALCULATED FROM SAMPLES FROM INDIVIDUALS 
CONSTANTS FOR 1906 CONSTANTS FOR 1907 
Population | Average Difference || Population | Average Difference 
M yules...... 8.1588 | 8.1538 .0050 || 7.3716 | 7.4532 .0816 
Standard deviation 
of ovules........ 1.1244 . 7673 -a57% 1.2225 . 8065 .4160 
Mean seeds....... .7149 . 7165 .0016 27427 . 7418 . 0009 
Standard deviation 
OL Seeds. sea: .8878 .8462 .0416 .9031 .8665 .0366 
Mean length of pod} 6.3356 | 6.3374 .0018 6.7570 | 6.7453 ‘ O1t7 
Standard deviatio 
of length of pod..| 1.3663 -9773 . 3890 1.3385 -9194 4191 
Correlation, length, 
VUES i .0652 .1281 .0629 .0261 . 1240 -0979 
peta length, 
ogni Oe - 3522 - 3867 0345 . 2019 . 3636 1617 
Chirlation, length, 
and *© Pines gab oe ie SQOIS ib eye Pesos 
ovule 
Consider the correlations. For both “populations” 7, is posi- 
tive, and, while not large, is significant in comparison with its 
probable error. In both series, 7, is positive, but numerically the 
values are too small to be of any practical significance. Both n, 
and 7, are lower for the general sample than for the means of 
individuals. 
§ Had the number of pods been: the same for all plants, or the plants weighted 
with the number of pods taken, both methods would necessarily have given the same 
results, 
* This result is at first rather puzzling. Generally the combination of several 
series of material raises r, but it is not necessary that — should always be the case. 
See footnote in a later section. 
