IN THE TROPICS : III. 



145 



grains already described, the pollen parents being the extract- 

 ed white recessives. 



F2 - 



There resulted (F 2 ) 1 cob with red pericarp and 39 percent, 

 of blue grains, and 11 cobs (plants) with white pericarps and 

 from 196 to 26-4 per cent, of blue grains. Details are given 

 in the accompanying table (36) : — 



1 

 2 

 3 



5 



6 



7 



8 



9 



10 



11 



12 



Table 36. 



Total. 



400 

 394 

 583 

 429 

 550 

 443 

 381 

 410 

 356 

 335 

 334 

 308 



Per cent. 

 White. 



Total 3,717 



1 ,206 



4,923 



Per cent. 

 Blue. 



39 

 21 

 24 

 27 

 22 

 19 

 23 

 26 

 19 

 21 

 23 

 24 



■0 



•8 

 •6 

 •5 

 •7 

 •7 

 1 

 •4 

 •6 

 •8 

 •4 

 •0 



24 5 



At first sight this would perhaps seem to indicate that the 

 female germ cells were produced in the proportion 3 white to 1 

 blue, but a reference to the evidence of the definite crosses 

 described in the first part of the paper renders it more prob- 

 able that we have here another case of irregularity in domin- 

 ance and no exception to the ordinary course of Mendelian 

 segregation. Another possible suggestion, that embryo and 

 endosperm might in some cases bear opposite characters, is 

 also shown to be inadmissible by the subsequent evidence, 

 which shows that the offspring of blue grains always included 

 some which bore the blue character. 



If Mendel's law of segregation is simply followed in the 

 present instance it is clear that some of the white grains 

 must be heterozygotes. because 50 per cent, of the total 



