216 THE PERPETUATION OF ADAPTATIONS 



while the yellow peas were found to be different; some pro- 

 duced only yellow peas while others produced yellow and green 

 peas again in the ratio of three to one. The pure yellow peas 

 were found on counting to be just one-third of the total num- 

 ber of yellow peas produced, or one-quarter of the total num- 

 ber of peas thus, i green: 2 mixed, i yellow. 



In reasoning out the significance of his results Mendel con- 

 cluded that something is carried into the germ cells which pro- 

 duces color in the seeds. One original parent contained a factor 

 for yellow, the other a factor for green, fertilization of the germ 

 cells from the two parents brought both factors into the ovule 



O 



Q 







FIG. 94. Diagram to show the segregation and re-combination of the factors 

 (black and white) in the gametes, and the presence of both in the hybrid F'. 

 (From Morgan.) 



which developed into the hybrid. Both factors do not come 

 out when the peas are formed, one recessive remains latent, 

 the other dominant predominates over the other with the 

 result that all peas are of one color, in this case, yellow. The 

 principle of dominance where two factors for the same character 

 lie together in the fertilized egg, was thus recognized. The 

 same reasoning is applied in respect to all other characteristics 

 of the adult organisms. 



Mendel's experiments were carried out long before the essen- 

 tial features of maturation were known, nevertheless he sug- 

 gested that some process must take place during the formation 

 of the hybrid germ cells whereby the yellow and green factors 



