Among 2052 F2 plants of crosses of ad1 with an1, no double recessive appeared, but F3 cultures from 220 F2 an1 and ad1 plants indicated a crossover value of 4.1%

2. Among 2052 F₂ plants of crosses of ad₁ with an₁, no double recessive appeared, but F₃ cultures from 220 F₂ an₁ and ad₁ plants indicated a crossover value of 4.1% (Linkage Summary, 1935, p. 32). Backcross cultures of last summer gave the following results:

Genes	Phase	XY	Xy	xY	xy	Total	% Recomb.
Ad₁ An₁	CB	247	7	10	199	463
Ad₁ An₁	RB	4	36	31	1	72
						535	4.1

R. A. Emerson