

ode ae ar Wee ey eee, cd à 
. _ by tee 
hi. 
T 
OF PARENTS BY THOSE OF THE CHILDREN. (20 tha? 
have the indices 85 and 75, are both homozygous, or, spoken in a gen- 
eral sense, at least hereditary variations. Accepting now that thehetero- 
zygotes are intermediate or that the high index is more or less domin- 
ant, but that at all events, there is a large variability of the hetero- 
zygotes, then the indices 80, 79 and 81 f. 1. can be such heterozygotes. If 
such intermediate heterozygotes marry, then among the children very 
much diverging indices may occur (for by segregation AA and aa ap- 
pear). In this way consequently the cases of table I arise. 
If persons with the indices 85 and 80, according to the formula 
AA x Aa, marry, then among the children there will be homozygotes 
with the index 85 and further heterozygotes with great variability, — 
in our example from 85—75. 
If on the contrary persons marry with the indices 80 and 75 accord- 
ing to the formula Aa x aa, then, among the children, there will be 
homozygotes with the index 75 and further heterozygotes with an in- 
dex varying from 75 to 85. In the first case the indices of children down- 
ward surpass those of parents in the second case upward and we get re- 
sults like the cases of the tables III and II. 
According to this explanation there must be among the children of 
the families of the tables II and III as many homozygotes as hetero- 
zygotes. So in table II half the number of children must have the index 
of the parent with the lower index, in table III of the parent with the 
higher index. 
We have made this calculation, but already now want to remark 
that it cannot be exact, because not all the cases of the formulae 
DR x RR (DD) = DR + RR (DD) have been brought into the tables 
Il and III (see p. 25, 33,43), but those only in which among the children 
takes place an evident surpassing of the indices in one direction. So we 
shall certainly find a too large number of ”"heterozygotes” (through the 
non hereditary variability). 
It may also be the case that there are in the tables II and III fam- 
ilies, which, as regards the hereditary constitution of the parents, be- 
long to table I. So, as far as regards the headform these parents segre- 
gate according to the formula Aa x Aa = AA + 2 Aa + aa, butinac- 
cordance to chance, in table II the aa-children and in table III the 
AA-children are lacking. Consequently in such families there will be 
among the children twice as many heterozygotes as homozygotes. 
Taking into consideration the presence of these families in the tables II 
