1027 



the two /'-forms. The iiiiijorilv lio\vG\ur of (ho F.^ plaiils sliow llio 

 mean lj])e. This also holds for (he crossing of Egyptian wi(li \vhi(e- 

 flowering (lax. Here also F^ shows, so far as size of seed is concerned, 

 a condnnous series of forms in which the mean is most strongly 

 represented. It was therefore not difficult to find in F^ and F^ a 

 certain number of plants which agreed in size of seed. Among these 

 w^ere blue-flowering ones which from investigation of their j^rogeny 

 were fonnd to be homozygous for the colour of the flower and 

 in this therefore were equal to the bine P-forms. At the same time 

 tliere were also white-flowering plants in this lot. These are always 

 homozygous and did not therefore require to be cultivated further. 

 Now since the size of the seed in these forms was the same, they 

 could independently of this point be compared as to their average 

 number of seeds. 



An investigation of these plants gave the following results. 1100 

 fruits from 94 homozygous blue-fiowering plants of F^ and F^ were 

 examined. These yielded 6468 seeds, an average of 5.88. 71 white- 

 flowering plants from F^ and F^ yielded in 800 fruits 4112 seeds, 

 an average of 5.14. These two mean values are intermediate between 

 those of the P-fornis, in connection with the size of the seed which 

 is also intermediate. But it further results that the white-flowering 

 plants have a smaller number of seeds in the fruits than the blue- 

 flowering ones, namely as 12.6°/„ less than the blue ones. This 

 difference cannot, when the large number of the observations is taken 

 uito account, be ascribetl to chance. 



A second cause of the aberrant numerical proportion is in this 

 way demonstrated. The question now remains to what extent 

 the deficiency in white-flowering plants can be explained by this 

 means. 



As stated above, out of the whole number of cultures 1043 white- 

 llowering plants might be expected theoretically. The difference in 

 the averiige number of seeds formed between the white and the 

 blue varieties amounted to 12.6"/o, i.e., for every 100 seeds of wdiite- 

 flowering plants 12.6 will be wanting. For 1043 seeds this would 

 amount to 10.43 X ^^2.6 ;= 131, from which a corresponding 

 deficiency in white-flowering plants will arise. 



By reason of both these causes together a deficiency of 

 100 -f" 131 = 231 white-flowering plants can be explained. The 

 deficiency actually amounts to 243 plants. The difference between 

 these two values is insignificant. It may therefore be considered 

 proved that the lesser germinating-power and the lesser number 

 of seeds per fruit of the white-flowering variety are the causes 



