1031 



Tlic j)rescii('e or al)seii('c of iliis factor is ovi'ii more intiiiialclv con- 

 nected with the niiinbci' of the seeds and their gerniinating-powcr 

 than the nature of the mother-plant which produces the seeds. For 

 seeds with the colour-factor and seeds without it are formed in ]'\ 

 by the same plant, even in the same fruit and yet the number and 

 the germinating-power of those without the colour-factor is less. We 

 see therefore that the difference between the white and blue varieties 

 of flax, so far as concerns the number of seeds and their germina- 

 ting-power, is unconnected with the difference in nutritional relation- 

 ships between the plants, hut only with the presence or absence in 

 the gametes of a factor for the colour of the flower. 



The following is a summary of results. 



In crossing white- and blue-flowering varieties of Ltnuin u.sitatls- 

 simum there are formed in the second and following generations 

 white and blue individuals in numerical proportions which are not 

 in agreement with those to be expected in accordance with Mekdel's 

 law of segregation. 



In all cases thei'e is according to the proportion 1 : 3 a deticiency 

 in white-flowering plants. 



The deficiericj^ arises from two causes which act in the same 

 direction: 1. By F^ and by the heterozygotes of the following 

 generation there is formed a relatively too small number of seeds 

 which will yield white-flowering plants. 2. The germinating-power 

 of the seed, thai yields wdiite-flowering plants is less than that of 

 the seed which produces blue-flowering ones. The smaller number 

 of seeds which yield white-flowering plants and the inferior germi- 

 nating-power of these seeds are both the result of the lower vitality 

 of the combination of two gametes both devoid of the factor for 

 the blue colour. 



The vitality of the gametes-combination and with it the average 

 number of seeds per fruit and the germinating-power of the seed 

 are 'more closely connected with the presence or absence in the 

 gametes of the factor for the floral colour than with the nature of 

 the plant, which |n'oduces the seed. 



Gronitujen, 9 January 1914. Botanical Laboratori/. 



