566 Curves of C o in po sitae and Unihelli ferae. 



During these three years the germinating power of 

 the seeds, and the individual strength of the whole cul- 

 ture increased considerably. In the first year I only 

 got the proper number of plants per square meter by 

 sowing a large quantity of seed; in the following year 

 less seed was sown and the crop was correspondingly 

 scanty: in 1894 more seed again was sown and many 

 seedlings had to be weeded out. 



The result of these observations is summarized in 

 the table on page 564. (See also Fig. 118.) 



Selection, we see, in this case has been unable to 

 effect any further alteration in the mean or in the am- 

 plitude of variation. It has simply maintained the mean 

 at the same point. 



We come now to Coreopsis tinctoria (Fig. 119 C). 

 The inflorescences of this beautiful composite have, as 

 a rule, 8 ray-florets. Yet this number varies on the same 

 individual as well as from plant to plant. I obtained my 

 seeds in the winter of 1891/92 from MM. Vilmorin- 

 Andrieux & CiE. of Paris, and tried simultaneously 

 to increase the mean number of ray-florets by manuring, 

 and to diminish it by selection. 



The result was that the mean number maintained it- 

 self almost unaltered at 8, that is to say that the effects 

 of the two opposing factors neutralized one another. 



My cultures in the years 1892, 1893, 1894 extended 

 over 1, 8 and 6 square meters respectively. I determined 

 no curve for the first year; the vast majority of the 

 plants had 8 rays; occasional ones 9 and 10; and fewer 

 still 11, 12 or 13. These were all pulled up: I only 

 saved a few, most of which had 7 ray-florets. 



In 1893 I had 495 plants; all those which had 8 or 

 more ray florets were pulled up as soon as the rays could 



