SEEDS AND SEEDLINGS 81 



to protect the delicate parts of the embryo from injury. The food 

 is in a form not easily dissolved by water or broken up by the 

 action of frost, so that it is kept in a hard state until such a time 

 as it can be softened by the process of digestion during the growth 

 of the plant. It can be seen that plants bearing seeds having 

 some of the above characters have a great advantage over plants 

 bearing seeds that are poorly protected. 



Problem XIII. A study of some methods of plant breeding. 

 (Laboratory Manual, Prob. A'///.) 



Plant Breeding : Variation of Plants. Examination of a row 

 of plants in a garden, of a hundred dandelion plants, or careful 

 measurements made on the pupils in a classroom, would show us 

 that no two plants and no two boys or girls have exactly the same 

 measurements or characters. Each plant or animal in a state of 

 nature tends to vary somewhat from its parent. This is a law 

 among plants and animals. 



But a second law exists which we also know something about. 

 A plant or animal hands down to its offspring some of the charac- 

 teristics which it possesses. Each one of us in some way resembles 

 our parents or, it may be, our grandparents. Each plant produced 

 from seed will be in some respects like the plant which produced 

 the seed. 



These two laws, of variation and of heredity, the bases on which 

 Charles Darwin explained his theory of evolution, are made use 

 of by plant and animal breeders. Since plants tend to vary and 

 since such variations may be continued in their offspring, plant 

 breeders have helped nature by artificially selecting and propa- 

 gating the plants showing the characters wanted. 



Selective Planting. By selective planting we mean choosing 

 the best plants and planting the seed from these plants with a view of 

 improving the yield. In doing this we must not necessarily select 

 the most perfect fruits or grains, but must select seeds from the 

 best plants. A wheat plant should be selected not from its yield 

 alone, but from its ability to stand disease and unfavorable con- 

 ditions. In 1862 a Mr. Fultz, of Pennsylvania, found three heads 

 of beardless or bald wheat while passing through a large field of 

 bearded wheat. He picked them out, sowed them by themselves, 



HUNT. ES. BIO. 6 



