124 Afaz'isni. 



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. ni. liitciiin. 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 rubniui and A. ma jits Intcuni. 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 tliose 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- 



