2. Zebra‑necrosis.

Zebra‑necrosis is linked with Og giving about 14.9% of recombination in a backcross population of 94 individuals (News Letter No. 22:42‑43. 1948).

The following data were obtained in a backcross with zn and g in a population of 253 individuals.

( + g )	x	zn‑g
zn +

Family	+ +	g +	+ zn	g zn	Total
48‑1525	13	20	22	13	68
48‑1526	6	22	29	3	60
48‑1527	10	21	25	5	61
48‑1528	8	23	27	6	64
Total	37	86	103	27	253

Recombination zn‑g = 25.3%

zn is to the left of g, but the present experiment is inconclusive

in establishing the position of zn in relation to Og. A three

point test is now being carried out including Og, zn and g.

J. M. Guevara