138 THE BREEDING OF ANIMALS 



that three great investigators, De Vries in Holland, Von 

 Tschermak in Austria, and Correns in Germany, simul- 

 taneously discovered the published results of Mendel and 

 recognized their great fundamental importance. 



131. The experiments of Mendel. Mendel selected 

 for his experiments the common garden pea. It is not 

 certain that he fully recognized the wisdom of making 

 such selections as were finally made for his work, but at 

 any rate he selected two varieties of peas differing in a 

 simple character but each firmly fixed in the parent 

 variety. The peas were also self -fertilizing, and accidental 

 mixture by cross fertilization was thus avoided. The 

 characters selected by Mendel were " purple or white 

 flowers," "yellow or green cotyledons," and " round or 

 wrinkled seeds." He found that all of these characters 

 were firmly fixed and bred true. These varieties were 

 crossed and the progeny were bred pure for many suc- 

 ceeding generations. 



He decided upon the simple character of color and* 

 selected a green seeded and yellow seeded variety. Recip- 

 rocal crosses were made, and from each cross the result- 

 ing peas were all yellow. Because the yellow color in 

 the cross appeared in every case, he called it the dominant 

 character; and the green color which did not appear in 

 the first generation was called a recessive character. 



All the yellow seeds of the first generation resulting 

 from the original cross were planted. In the second 

 generation Mendel discovered that both green and yellow 

 seeds appeared. In calculating the relative proportion 

 of the two colors, he found that about one-fourth of the 

 seeds were green and the remaining three-fourths yellow. 

 The green seeds and yellow seeds were planted separately 

 and it was found that the green seeds produced only 



