Heredity and its Bearings on Atavism. 147 
ovum only one sex cell out of a possible of eight matures, 
while normally all eight male cells become spermatozoa; and 
secondly, on the vigour of the respective male and female 
segments. 
In the ovum I should suppose those segments to remain 
which were the strongest, either male or female ones, or if 
these be equally strong, one male and one female. In the 
spermatozoan, if division be equal, I should expect one 
paternal and one maternal segment respectively. From my 
standpoint then, the male cell gives rise to greater variability 
than the female cell. 
The reappearance of the characters of the grandparents 
would seem to depend on the special development of those 
segments derived from the respective grandparents. If, e.v., 
a female individuum A receives two chromatin segments w 
and « from its father, and other two y and z from its mother, 
we may assume wand «# to be less vigorous than y and z; and 
this circumstance would call forth a special activity of y and 
2, with the result that A would resemble its mother more 
than its father. A on forming her sex cells would retain in 
the ova the more vigorous segments y and z, and these, - 
should they meet again with feeble male segments, will have 
been exercised during their existence in A to such an extent as 
to impress in a very marked way their characteristics on the 
new individuum B, which latter will show in a correspond- 
ingly evident manner its resemblance to its grandmother. 
Another possibility, however, is this, that the segments 
y and z may have been weakened through having been 
forced to work in company with the still feebler w and 2. 
If this be the case, and if they meet during fecundation 
vigorous male cells, they will be able to play only a second 
role during the ontogeny of B, and then the male cellular 
organs will make their supremacy felt. Again, however, the 
traits of one grandparent will tend to predominate. 
Partial Atavism, i.e, a resemblance to grandparents in 
some points, may similarly be accounted for on the sup- 
position that, during ontogeny, either the paternal or the 
maternal cellular organs undergo a special development in 
the respective organs of the metazoon or metaphyton. 
