244 HARRIS: RELATIONSHIP OF OVULES TO SEEDS 
C. A collection from 26 trees near Sharpsburg, Athens County, 
Ohio; 3,900 pods. 
The pods of Cercis canadensis are, like those of many other 
Leguminosae, somewhat unsatisfactory for investigations of 
fertility because of the difficulty of drawing a sharp line between 
ovules which fail to develop and those which form perfect seeds. 
It seems unfeasible, in the present state of our knowledge of these 
matters, to adopt more than the two categories, abortive ovules 
and matured seeds. In most cases, an observer will have little 
difficulty in determining to which class an individual ovule should 
be assigned. Nevertheless, we are dealing here with characters 
not perfectly discontinuous. This condition must always be 
borne in mind in considering the trustworthiness of our constants. 
In counting, we considered as abortive ovules only those which 
had not developed at all, or only slightly, beyond the stage at- 
tained in the very young pod. Some of the seeds counted as 
matured were probably not well enough developed to be viable. 
Some of them were light and apparently blighted. The cause of 
this I do not know. The ovules failing to develop are not as 
easily made out in the mature pods of Cercis as they are in some 
other Leguminosz; this increased somewhat the labor of counting. 
III. Discussion or DaTA 
A. The Meramec Highlands Collections 
The correlation between the number of ovules formed and the 
number of seeds developing in a first large sample of 6,000 pods, 
chiefly from a few (6 or 8) large trees growing closely together is 
shown in Table I. For comparison another 4,000 was gathered 
quite at random in the immediate neighborhood of the trees 
furnishing the first 6,000, but from a larger number (probably 25) 
of smaller trees: Table II gives the correlation surface. 
The fundamental physical constants appear in Table III. 
For the means the differences and probable errors of the dif- 
ference of these two samples are 
OVINES 5 Obes Sek +.1536 =.0137 
BOOBs oie een cy eds es —.0261 +,0166 
