1. A viable pale green character easily classifiable as seedling and up to time of flowering was found in an F₂ population in a 3:1 ratio. Subsequent tests showed that this character is due to duplicate genes. One of these genes is in chromosome 6. The following data were obtained:

B. C. for Y and Pl and for the two pg genes

Y	y	Y	y	Y	y	Y	y
Pg	pg	pg	Pg	Pg	pg	pg	Pg
Pl	pl	pl	Pl	pl	Pl	Pl	pl
661	319	92	176	178	40	3	337

From these data the linear order and recombination values are:

Y‑‑20.9‑‑Pg‑‑9.5‑‑Pl

In one family the pg gene not in chromosome 6 was homozygous and a B.C. ratio of one green to one pale green was found. These data are:

Y	y	Y	y	Y	y	Y	y
Pg	pg	pg	Pg	Pg	pg	pg	Pg
Pl	pl	pl	Pl	pl	Pl	Pl	pl
128	93	32	23	27	11	3	1

Here the linear order is as above but slightly different recombination values were obtained:

Y‑Pg 18.6

Pg‑Pl 13.2