Obliteration of Effect of Nutrition by Selection. 571 



The amplitude of variation Q/M is intermediate be- 

 tween those of Oenothera (0.08) and Anethnm (0.16). 



We come now to the second series of experiments, 

 carried out with Madia elegans. 



This species is more suitable for experiments with 

 selection than either Bidcns or Coreopsis. In the first 

 place the growth is much more uniform especially in 

 youth ; in the second, the number of ray-florets is consid- 

 erably larger ; and — last and most important point of all — 

 there is m^uch less partial variability in this case. This 

 means that the various inflorescences on the same ])Iant 

 differ from one another only slightly in the number of 

 their rays (at least in my race) so that the numl)cr on 

 the terminal inflorescence can be more justly regarded 

 as characteristic of the whole plant. 



I obtained the seeds from Messrs. Ha age & Schmidt 

 in Erfurt. I sowed them in 1892 over a square meter of 

 soil. Most of the individuals had 21 ligulate florets, 



