114 lock: studies in PLANT BREEDING 



only a few caa a did the yellow colour appear to be fully 

 dominant. It will however be convenient in practice always 

 bo call the white or non-yellow character "recessive," and 

 tlii-> procedure is justified by thp fact that it was always 

 ible bo distinguish the recessive (so defined) from the 

 beterozygote form. 



F 1. 

 The immediate result of crossing. 

 (a) White x Yellow. 



Erpt. 25 — White dent x Yellow dent. — 



The starchy apical part of the "xenia' grains resulting 

 ti 'in this cross remained nearly pure white whilst the lower 

 part took on a pale yellow tint, the colour varying slightly in 

 different grains. 



(b) Yellow x White. 



Erpt. 26. — Yellow dent x White dent. — 

 In these grains the colour of the apical part became chang- 

 ed from strong yellow to very pale yellow, whilst the lower 

 part remained deep yellow and showed scarcely any alteration. 

 The grains as a whole were thus very much yellower than those 

 which resulted from the reciprocal cross. 



Expi. 27. YeUow pop corn x G. W. S. — 

 The cross-bred grains showed no change in colour as com- 

 pared with those of the yellow parent, yellow being in this 

 dominant. (The reciprocal cross was not made.) As an 

 eption, one planl oul of many raised yielded nearly equal 



numbers of while and of yellow grains; namely, 132 W and 



Ml N The conclusion bO be drawn from this is that the 

 biculai (lower of the parental strain, winch gave rise to 



bhe grain from which this plant sprung, must have been 

 idenl illy fertilized with pollen from a smooth white variety 



The unknown parent must have been starchy because all 



the grains of bhe plant under consideration were starchy. 



although the p. 'Men parent was SUgaiy. 



