124 Atavism. 
be lacking on whole spikes and sometimes on entire 
plants. But such absence is only apparent; closer in- 
spection will reveal the existence of very fine red stripes. 
I never found a branch on which they were quite lacking, 
nor a plant, nor even a twig which had reverted to the 
variety, A. m. hit cum. On inflorescences on which the 
striping is very meager it may sometimes occur that on 
a single flower no stripes can be found ; but this is merely 
an extreme case of that partial variability which all 
organisms exhibit. 
This negative result based on eight years' experience 
is important because it shows us that we are not dealing 
here with a segregation into two components, e. g., A. 
ma jus rubrum and A. ma jus hit cum. If we want to speak 
of a segregation the two units would be the red striped 
and the uniformly red form. 
A glance at a bed of these plants is sufficient to re- 
veal the fact that the breadth of the red stripes exhibits 
individual variability; moreover that, as might be ex- 
pected, plants with very fine and those with very coarse 
red stripes are the rarest. In 1897 I tried to find out if 
it were possible to express this variability in the form of 
a curve. At first it seemed impossible to obtain an ac- 
curate measure of the striping, for it seemed practically 
unfeasible to determine the sum of the breadths of all the 
stripes in a flower and to express this sum in proportion 
to the circumference of the corolla. I succeeded, how- 
ever, in attaining my object in the following way : I had 
the average flower on the main stem of every plant in a 
bed picked by an assistant, and then I endeavored to ar- 
range these in a series according to their color, ascending 
from the almost yellow to the completely red. With a 
group of between one and two hundred flowers this sue- 
