92 Missouri Agricultural Report. 



Fig. 2 shows us how many kinds of seed our hybrid plant can 

 produce. Half of its ovules are red and half white. We can readily 

 see that the red ovule is just as apt to unite with red pollen as 

 white pollen, hence, on the average, half of the red ovules will 

 unite with red pollen and half of them with white. Likewise, half 

 of the white ovules will unite with red pollen and half with white. 

 We thus have four cases, namely : red uniting with red ; red with 

 white ; white with red ; and white with white. Each of these four 

 cases is as likely to occur as another. Hence, on the average, they 

 will occur an equal number of times, especially if the number of 

 seed produced is large. Thus we see that the progeny of our 

 hybrid is one-fourth pure red, one-half hybrid between red and 

 white, and one-fourth pure white. But since the hybrids also 

 produce red flowers, the progeny of the hybrid we are considering 

 will be three red to one white. This is the well known Mendelian 

 ratio found in the progeny of a hybrid plant or the progeny of two 

 hybrid animals. 



We must now get acquainted with two very big words, because 

 we have no little words that fit the case. The first kind of seed 

 shown in Fig. 2 is formed by the union of red with red. This 

 seed, and the plant it produces, is said to be homozygote, a word 

 derived from the Greek and meaning ''like things united." The 

 fourth kind of seed is seen to be homozygote for white. The second 

 and third types consist of unlike things united, and are therefore 

 said to be heterozygote. We shall have to use these words fre- 

 quently in what follows. 



As the separation of character pairs is highly important, I 

 will take the liberty to use another illustration. Suppose that the 

 parents of a family of children are both heterozygote for brown 

 eyes and blue eyes. Since brown is dominant to blue both these 

 parents will be brown-eyed, but each of them will transmit brown 

 eyes to half the children and blue eyes to the other half. (Fig. 3.) 

 The possible types of children in such a family are illustrated in 

 Fig. 3. The first group consists of children which inherit : 



