THE GERM-PLASM THEORY 



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and one-fourth green. This proved that the seeds 

 of the first generation (Fi), although yellow, still 

 possessed within them the factor for greenness in a 

 latent condition. Green was therefore called a re- 



SPERM 







Fs 



FIG. 81. Diagram to illustrate Mendel's law of segregation. Individ- 

 uals (zygotes) are represented by superimposed circles, whose colors 

 stand for the factors involved. Gametes (germ cells) are represented 

 by single circles. (From Morgan, 1914-) 



cessive character and yellow a dominant character. 

 As a result of breeding the (F 2 ) second generation it 

 was found that all of the green seeds produced plants 

 which bore green seeds ; that is, these plants were 

 pure green and "homozygous" as regards color; 

 whereas the plants which bore yellow seeds could be 



