CONFIRMATIONS OF MENDEL'S LAWS 357 



starchy character dominates. When an egg-cell of the wrinkled 

 sugar-maize stock is fertilised by a pollen-cell of the round 

 starchy stock, the result is a round seed with starchy endosperm. 

 If this seed is sown, it becomes a plant which, on self-fertilisation, 

 forms a cob with a mixture of round starchy and wrinkled 

 sugary seeds in the ratio 3:1. The wrinkled seeds yield sugar- 



** A 



4 R 



^Pf*^ 



p.. 



D(R) 



flP^Pp(R) ^D(R), 



DD D(R) DM RR OD D(R) 0(R) .RR 



F 3 



FIG. 38. Diagram showing Mendelian phenomena in nettles. (By 

 permission of Prof. Correns.) 



P l , leaves of the two parents ; D, Urtica pilulifera ; R, Urtica dodartii ; F 1 , leaf of the 

 progeny, D(R), the serrated type being dominant ; F 2 , leaves of the hybrid's offspring ; iDp 

 -f 2D(R) + iRR ; F 3 , leaves of the next generation ; DD, pure extracted dominants ; RR, 

 pure extracted recessives ; D(R), impure dominants. 



maize ; the round seeds yield two " impure rounds " to one 

 " pure round." Correns has observed a very interesting case 

 in which two pairs of contrasted characters are implicated. 



One variety, Zea mays alba, which has smooth white seeds, 

 was crossed with another variety, Zea mays coeruleodulcis, 

 which has wrinkled Uue seeds. The hybrids (F 1 ) had smooth 



