Mendel's Second Law is Blemished

The chromosome theory of inheritance is born in two decades following the discovery of Mendel's work.

Bateson and Punnett encounter a strange dihybrid ratio in using purple vs red flower color and round vs long pollen grains in Sweet Pea (Lathrus).

P₁ - Purple Long x Red Round

F_1- all Purple Long

			Number of Progeny
Phenotype	Genotype	Expected Ratio	Observed	Expect
Purple, Long	P_,L_	9/16	284	215
Purple, Round	P_,ll	3/16	21	71
Red, Long	pp,L_	3/16	21	71
Red, Round	pp,ll	1/16	55	24
			381	381

Thomas Hunt Morgan investigates Fruit Flies ! Wins Nobel Prize in 1933

by Kenneth G. Wilson,
Professor of Botany
Miami University
wilsonkg@muohio.edu