The Stature and Chromosomes of Oenothera gigas, De Vries. 543 
size of flower parts. These measurements were not intended to be 
statistically aceurate nor to inelude the whole ränge of Variation, but 
are snfficient for the present comparison. It will be seen tliat the 
measurements are larger for 0. gigas in all but three cases, which 
are lengtli of filament, length of Stigma lobes, and length of capsule. 
It also appears tliat in 0. gigas the anthers are approximately twice 
their length in most of the other forms. From Table III it will be 
seen that the average "length” 1 ) of the epidermal cells of the anther 
in gigas is an increase of 72.8 % over their "length” in Lamarckiana, 
while the average "width” of these cells is only increased 28 A%. 
Similarly the stigma cells show a greater proportionate increase in 
length than in width. But in the petal epidermis the cells show a 
greater increase in width than in length. 
It is probable theu that the number of cells in the two anthers 
is approximately the same, and the greater length of the anther in 
gigas is accounted for by the greater length of the individual cells. 
There is evidently some regulative factor determining 
that the increase in "length” of the epidermal cells shall 
be greater than the increase in their "width” in the anther 
epidermis, but less in the petal epidermis. In other words, 
the cells are not simply larger in all their dimensions, but the 
increase has been greater in one dimension than in another, resul- 
ting in a change in the relative dimensions of the cells. This in all 
probability accounts for the altered shape of some of the Organs, 
such as the leaves and capsules. Whether this change in the rela- 
tive dimensions of the cells in certain tissues results from the fact 
that the cells, being larger, require readjustment in dimensions, or 
whether this readjustment is due to separate factors in the plant 
acting during development, cannot be determined at present. But it 
is at least possible, that the only original change was in the doublin g 
of the chromosome number, the larger nuclei, cells and organs and 
secondly the changed size relations of the cells and hence the changes 
in the shape of certain organs, all resulting from or being corre- 
lated with this initial doubling in the number of chromosomes. In 
0. gigas we have an organism built of bricks which are 
larger and whose relative dimensions are also altered in 
some cases. These two factors will apparently account 
J ) The terms ‘'length” ancl - ‘width” for the epidermal cells are here used 
in the sense defined earlier. 
36 * 
