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 white 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

Text iGenetics by Peter J. Russell

This web site is provided for instruction in Botany and Zoology 342

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