146 Proceedings of the Royal Physical Society. 
and that they ‘have definite functions to fulfil; and we 
may assume that the features of an individual depend on 
the manner in which the various functions necessary for life 
are fulfilled by the cell organs. 
Thus in a zygote, the “paternal” nuclear segments will 
meet their homologues, the maternal ones, and theoretically 
one of the following events may occur :— 
(1) The maternal and paternal organs, ey., chromatin seg- 
ments, may be equally vigorous; they may be equally affected 
by the environment, and they may carry on their work in 
harmony. If this be the case, the embryo, on reaching 
maturity, will be unlike either parent, for its features will 
be the result of the blending of those seen in the parents. 
(2) The segments derived from one parent, say the 
mother, may be primarily the stronger or more vigorous, 
and the environment may suit them better than it does the 
“paternal” segments. Hence during ontogeny the maternal 
cell organs will undergo a special development, and will 
provide the embryo with such nourishment as the mother- 
individuum was accustomed to, and the embryo will show in 
a more or less pronounced form the features of its mother. 
This influence of the maternal cellular organs extends, 
however, not only to the embryo as an individual, but also 
affects the paternal cellular organs, which latter may be 
strengthened or still further weakened. 
We have also seen above that mature sex cells contain 
only one-half the number of chromatin segments possessed 
by either the immature sex cells or the somatic cells. 
The question arises, What will be the distribution of the 
segments at the time of formation of the mature sex cells ? 
Let us consider the case of Ascaris megalocephala, the 
immature sex cells of which contain four chromatin seg- 
ments, two of which were derived from the father, while the 
two others were got from the mother. These four segments 
may evidently be distributed in such a way that each mature 
sex cell receives either the two maternal or the two paternal 
segments, or one maternal and one paternal segment. 
Which it does receive will depend, firstly, on the number 
of fully formed sex cells which reach maturity—thus in the 
