1 6 THE ESSENTIALS OF AGRICULTURE 



cotton (Fig. 10) produces hybrids bearing only long-staple cotton. 

 Polled cattle when crossed with horned cattle (Fig. n) produce 

 offspring none of which have horns in the first generation. 

 When trotting and pacing horses are crossed, all the offspring 

 in the first generation trot. 



17. The appearance of succeeding generations. It was also 

 found by Mendel that in the generations following the first 

 hybrids the dominant and recessive characters would appear in 

 definite proportions. For example, if the smooth-seeded peas 

 which were produced as hybrids in the cross between smooth 

 and wrinkled peas were sown, one fourth of the seeds they 



FIG. 10. Long-staple and short-staple cotton 



When long-staple and short-staple cotton are crossed, all the fibers in the first 

 generation are long staple 



produced would be wrinkled, while three fourths would be 

 smooth. If the wrinkled seeds were then sown, they would pro- 

 duce plants bearing only wrinkled seeds. But if all the smooth 

 seeds were again sown, one third of them would produce plants 

 bearing smooth seeds, while the other two thirds would bear 

 both smooth and wrinkled seeds in the ratio of 3 : I, as at first. 



In every generation after the first there thus appear to be 

 two kinds of seeds, of which one fourth are wrinkled and three 

 fourths are smooth. After the first generation, however, there 

 are really three kinds of seeds, although this fact is not evident. 



I. One fourth are smooth seeds and grow into plants that 

 produce smooth seeds that come true. 



