204 MAKING BETTER PLANTS 



the new type has become "fixed." This is because 

 offspring, as a rule, inherit more from the immediate 

 parents than from grandparents, and more from grand- 

 parents than from great-grandparents, and so on. 



(3) If the new plant can be propagated asexually, the 

 breeder will of course use this method. One illustration 

 of its advantage has been given. The propagation of 

 new kinds of apples offers another familiar illustration. 

 New varieties are first obtained as seedlings. But, be- 

 sides the time involved, the seeds from these seedlings 

 cannot be trusted to resemble the new type. They show 

 a remarkably strong tendency to variation as well as to 

 reversion. Now and then a seed may produce a valuable 

 and still newer variety ; but, to perpetuate the chosen 

 one, the breeder propagates it by grafting. 



152. What Mendel l Taught Us. Mendel found that 

 plants were made up of what he called unit characters, 

 such as height, color, and shape. Assuming that a young 

 plant had 100 unit characters, he discovered that 50 came 

 from the pollen parent and 50 from the pistil parent. He 

 found also that in hybrids, or crosses between two different 

 but closely related kinds of plants, these unit characters 

 appear according to a mathematical law. When he took 

 the pollen from white-flowered peas and placed it on the 

 pistil of red-flowered peas, he found the next season that 

 the hybrid bore only white flowers. The influence of the 

 red-flowered parent was suppressed as far as the color 

 unit of the flower was concerned. But when he planted 



1 Mendel, an Austrian monk, was born in 1822 and died in 1884. His 

 simple experiments in the garden of bis cloister, especially with peas, have 

 thrown a flood of light on Nature's great principle of heredity. His scientific 

 work was not generally appreciated during his life-time ; its significance was 

 not then understood. In 1900, however, his papers were " rediscovered." 

 The nature of his researches was then made known to the scientific world, 

 and Mendel and his great work began to be rated at their proper value. 



