[Chap. XXXVII 



HEREDITY IN PLANTS 



45.' 



One of the chromosomes 



in a sperm from 

 the red -flowered plant 



One of the chromosomes 



in an egg from 



the white -flowered plant 



generation 



Two of the chromosomes in 



the fertilized egg and 



hence in the vegetative 



cells, microsporocytes, and 



megasporocytes of the 



plant that develops from 



this fertilized egg 



r 



Possible kinds of sperms and eggs with respect to 

 these two chromosomes that can be produced in this plant 



A 



Sperms 



and 



Eggs 



Possible chances of 



fertili:ation if only 



self-fertiliiation occurs 



Possible kinds of 



chromosome complements 



in the fertilized eggs 



and subsequent cells of 



the various plants of 



the F2 generation 



Fig. 212. A diagrammatic representation of the relation of chromosomes and 

 factors of flower color in snapdragon. 



the egg from a dwarf hairy plant has a gene (d) that conditions height 

 and another gene (h) that conditions growth of hairs on the epidermis. 

 If we use the suggested letters as symbols for the genes that condition 

 the development of these characters, we may represent the distribution 

 of these two kinds of chromosomes in the plants of the Fi and F2 genera- 

 tions by a diagram (Fig. 213). 



All the plants of the Fi generation were tall and smooth like one of the 

 parents, showing that the genes that condition the development of tall, 



