SOME PRINCIPLES OF PLANT BREEDING 469 



paper bag before it opens. The pollen is applied in various 

 ways according to the necessities of the case. In large opera- 

 tions it is often applied by the fingers. In other cases with a 

 camel's-hair brush, but this is objectionable in smaller operations 

 and where one is pollinating several different varieties, for there is 

 danger of pollen adhering to the brush when the next variety is 

 taken up. Some use a pointed scalpel made by inserting the 

 head of a pin in a small stick and pounding the pointed end 

 into a thin blade. After the pollen is applied to the stigma the 

 flower is again covered with the paper bag, until the receptive 

 stage of the stigma is passed. In some cases bags of gauze are 

 used which exclude the insects, and in case the fruit or seed is 

 large enough it is caught and saved, in case, at maturity, the 

 fruit or seed should fall before being harvested by hand. In 

 some cases thousands of these seeds are obtained and planted in 

 order to have as wide a range of variation as possible to select 

 from. 



654. Selection in plant breeding. Artificial selection, that 

 is selection by man, here merely replaces natural selection. 

 Plant breeding by artificial selection has long been practiced by 

 man, so long that we do not even know the origin of some of our 

 most important domesticated plants to say nothing of the early 

 history of their development and improvement. The practice 

 began with man in his savage state. It is only during recent 

 years that civilized man has kept any record of the origin of new 

 forms, and many of these have so far departed from any feral 

 species at present known that we cannot now trace the history, 

 nor in some cases determine what species might have been 

 the parent of the form now in cultivation. The origin of some 

 is known while that of others is a matter of conjecture. 

 The origin of many of the more recent introductions is com- 

 paratively well known, and the pedigree of some has been quite 

 accurately kept. As soon as savage man began to apply the 

 principle of selection and cultivation even on a crude scale, 

 the fruits, grains and vegetables which formerly he collected 

 from feral plants became more productive, larger and of better 



