VARIATIONS 



633 



bearded 



I 



appeared in 1791 in Massachusetts. This ram had such short legs 

 that it could not jump fences. Hornless cattle, albinos, and the 

 famous beardless wheat found by Mr. Fultz are examples of such 

 variations. These are called mutants or sports. The term "mu- 

 tant " has of later years been associated with the Dutch naturalist, 

 Hugo de Vries. Very rarely, as he found, 

 chance mutations appear which breed true. 

 In the evening primrose, for example, he found 

 eight different mutations. This means that 

 new species in nature may arise suddenly, in- 

 stead of by very slow degrees, as Darwin be- 

 lieved. The reason that such variations as 

 these always breed true is because the germ or 

 sex cells of the animal or plant are affected and 

 thus the variations can be handed down to the 

 next generation. It is easily seen that such 

 variations would be of immense value to breed- 

 ers, as plants and animals much unlike their 

 parents might be formed and perpetuated. 

 About 1910, a bean mutant appeared in the 

 South which was adapted to life in the cotton 

 belt. As a result, more than 6,000,000 acres of 

 these beans were grown by 1917. Mutants 

 have appeared in tobacco, barley, wheat, oats, 

 tomatoes, and potatoes. One of the important parts of the work 

 of the plant breeder is to discover, isolate, and breed useful 

 mutations. 



Practical Exercise 14. Read and report to class something about the Kfe 

 and work of De Vries. 



Practical Exercise 15. Make a list, using any source material, of at least 

 ten plants and five animal mutants. 



Practical Exercise 16. What type of variation is probably seen in the 

 curve you constructed as the result of your Laboratory study on page 631 ? 



Selective planting. By selective planting we mean choosing 

 the best plants and planting their seeds with a view of improving 

 the yield in some definite ways. In doing this we must not neces- 

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

 from the best plants. Experiments in corn selection at the Uni- 



W¥^ 



/beardless 



The beardless wheat is 

 a mutant of the bearded 

 wheat. 



