IN THE TROPICS : III. 157 



As was previously stated, cob No. 5 of generation P possessed 

 a dark red pericarp, and 10 out of some 500 grains showed blue 

 pigment in the aleuron layer. The offspring of one of these 

 blue grains yielded on self-pollination 59" 5 per cent, of blue 

 grains— F^ (Cp. Expt. 56.) 



F2. 



Expt. 69. — A number of these blue grains were sown and the 

 plants arising from them received pollen from plants of white 

 dent. Cobs bearing F 2 grains were gathered from 30 plants, 

 and three of them had either exclusively blue grains (1 plant) 

 or 1 or 2 white grains only (2 cobs). All three of these 

 cobs showed the red pericarp colour. In the remaining 

 cobs the proportion of blue grains varied considerably, being 

 as follows in the case of 6 cobs which had white pericarps : 51 , 

 46, 42, 24, 23, and 20 per cent, of blue. These figures give of 

 course no idea of the statistical distribution of the percentages 

 in F2, but they serve to indicate a general agreement in range 

 with that shown in Expt. 66. 



F3. 



Expt. 70. — Grains from the cob with exclusively blue aleurone 

 layers were next sown and the plants again pollinated from 

 a further generation of white dent. The proportion of blue and 

 white grains was counted in the case of one cob from each of 

 58 plants, and the percentage of blue grains was found to range 

 from 54 to 26, the modal value being approximately 37 per 

 cent. 



Table 45 and fig. 3 (the black line) show, then, the effect 

 of pollination by white upon grains of a similar origin to 

 those in the case of which the effect of mutual pollination 

 was shown in Table 43. The present case differs notably from 

 the latter in the fact that only a very small proportion of the 

 plants showed dominance of blue in all the heterozygote 

 grains produced by them. 



