PLANT BREEDING 



427 



corn). In hybridizing corn it is only necessary to tie a paper 

 bag over the ear before the silk appears, in order to keep off 

 stray pollen, and leave it covered until full-grown ; then re- 

 move the bag, dust the silk thoroughly with pollen from tas- 

 sels of the desired crossing variety of corn, and thereafter keep 

 the ear covered until the silk is entirely withered. Sometimes 

 in hybridizing corn the stalks are detasseled just before the 

 ears are ready to receive pollen. If all the stalks 

 of one kind or one row are thus detasseled, it 

 is made probable that pollen, if received at all 

 by the ears of the detasseled stalks, must come 



from another row 

 or another kind of 

 corn. The detas- 

 seling of alternate 

 rows is a rather 

 common mode of 

 insuring cross-pol- 

 lination. In most 

 cases of hybridiz- 

 ing with bisexual 

 flowers it is nec- 

 essary to carry out 

 processes similar to 

 the following ones : 



(1) Select the flower to be pollinated before it opens or 

 its own pollen is mature. If it is one of a cluster of flowers, 

 as in the wheat or the apple, remove from the cluster of the 

 flowers all that are not to be operated on. 



(2) Open the remaining flowers and remove the stamens 

 by taking hold of the filaments with fine forceps, or cut away 

 all the stamens at once, as shown in Fig. 338. Then cover the 

 flower or the entire twig with a paper bag until the stigma 

 is mature. 



(3) When the stigma is mature, pollinate it with the de- 

 sired kind of pollen. This may be done with the finger tip, or 



FIG. 338. A peach flower prepared for hybridization 



A, flower cut round for removal of the stamens, with 

 the removed parts of the young flower showing above ; 



B, longitudinal section of a flower showing level (s) 



at which the cut was made in A 



