ROUND 



WRINKLED 



2n 



Meiosis 

 n 



Fertilis*^ 

 2n 



Meiosis 



n 



Fertilis'^ 

 2n 



MEIOSIS 

 GAMETES 



AND 



FERTILIS'* 



2n 



Fig. 7. — Mendel's experiment of crossing round and wrinkled peas. The parent 

 strains (P) were true breeding, giving only one kind of gamete (small circles) each. 

 The hybrid between them (Fj) was round seeded, but gave two kinds of gamete 

 in equal numbers, one like the gametes from the round parent and the other like 

 the gametes from the wrinkled parent. When pollen of the two kinds fertilizes embryo 

 sacs of the two kinds in random proportions, three round seeded peas are obtained 

 on the average for every wrinkled seeded pea in Fg. The wrinkled peas and one-third 

 of the round peas of F2 are true breeding like the original parents, but two-thirds 

 of the round peas resemble F^ in constitution and again give the 3 : i segregation 

 in F3. The chromosome cycle of reduction and fertilization is shown in relation 

 to Mendel's observations on the right of the diagram, where 2» is the somatic and n 

 the gametic number of chromosomes. 



