MENDELIAN INHERITANCE IN WHEAT 

 (After R. H. Biffen.) 



A. Stand-up wheat, \vith no beard, the one parent. 



B. Bearded wheat, the other parent. 



C. The hybrid offspring, with no beard. 



This shows that the beardless condition is dominant and the 

 bearded condition recessive. 



GRAND 



OFFSPRING 



BODY 



G.I. 



G.2. G.3. 



THE IDEA OF GERMINAL CONTINUITY 



G4- 



Gi. A fertilised ovum developing into a lineage of body-cells (B 3 ) and a lineage of germ-cells (the dark thick base-line). G2. Germ- 

 cell which starts the offspring of the next generation, with its body-cells (B^) and its germ-cells along the base-line. Gj. A germ-cell 

 starting the grand-offspring, with its body-cells (B 4 ), e.g. ectoderm, mesoderm, and endoderm, and likewise its germ-cells along the basal 

 "germ-track," Gj to G4. 



The base-line represents the lineage or chain of germ-cells; B a , B 5 , B 4 are the bodies of three successive generations which fall off from 

 the chain. The fundamental idea is that a fertilised egg-cell gives rise to a body and the germ-cells of that body. 



