202 A Contrihution to the Problem of Homotyposis 
I used the first 26 pods taken from 112 trees. The desirability of working 
with a larger series of data from individual trees then appealed to me and a table 
comprising the first 100 pods from the 60 trees from which that number could 
be secured was undertaken. For both of these series all the possible direct and 
cross homotypic correlations were ascertained for the fertility characters. 
The Kansas series comprised only 22 individual trees, from each of which 
100 pods were comited. The Ohio series included 150 pods each from 26 trees. 
For these two series all possible homotypic correlations for the fertility characters 
have been determined. 
III. Methods. 
The three direct intra-individual or homotypic correlations are : 
(1) Ovules of first pod and ovules of second pod, Tables I, II*. 
(2) Seed developing in first pod and seed developing in second pod. Tables 
III, IV. 
(3) Ovules failing in first pod and ovixles failing in second pod. Tables V, VI. 
The cross-homotypic relationships are : 
(4) Ovules of first pod and seeds developing in second pod. Tables VII, VIII. 
(5) Ovules of first pod and ovules failing in second pod. 
(6) Seeds developing in first pod and ovules faifing in second pod. 
Tables for two of the cross correlations are unnecessary. Thus for the relation- 
ship between the number of ovules in the first pod and the number of ovules failing 
in the second pod, fg^f,^, the slope of the regression fine is clearly 
or in terms of correlation 
'»l/2 ' 0x0-2 'ois-2 : 
'-'0\ "Ol '^01 
r , = r ^ - r (i) 
Again, for number of seeds in the first pod and number of ovules failing to develop 
in the second pod the slope of the regression straight line is 
0-si C^si 
whence r^,/, = r,,„, - r,^,^ ^ (ii) 
In calculating the correlations for length of pod in the Meramec Highlands 
series and for the fertility of characters of the Ohio and Kansas series I have had 
recourse to the direct and cross intra-class correlation formulae (v)-(xii) of 
* The numbers refer to the tables for the Meramec Highlands series. 
