278 MANUAL OF AMERICAN GRAPE-GROWING 



true that mutations seem to occur rather often in grapes, but 

 they are easily confused with variations due to environment 

 and are usually too vague to lay hands on. Until the causes of 

 these mutations are known and until they can be produced and 

 controlled, but little can be hoped for in the amelioration of 

 grapes through mutations. 



HYBRIDIZING THE GRAPE 



Hybridization has been the chief means of improving the 

 grape. At present, from what is being accomplished by many 

 workers, it looks as if it will long continue to be the best means 

 of improving this fruit. Since the grape-grower must depend 

 on new varieties for progress, as old varieties cannot be changed, 

 it should be the ambition of growers to produce varieties better 

 than those we now have. Many amateur and professional 

 grape-growers in the past have found breeding grapes a pleasing 

 and profitable hobby, so that much knowledge has accumu- 

 lated in regard to manipulating the plants in hybridization, 

 and the results that follow in the offspring of hybridization. 



Hoiv to hybridize. 



It is assumed that the reader is familiar with the botany of 

 flowers and the essential principles in crossing plants. If he 

 is not, he must carefully study the structure of flowers, especially 

 those of the grape, so as to be able to distinguish the different 

 organs and to discover when the pollen and stigma are ready for 

 the work of pollination. He should, also, read any one of several 

 current books on plant-breeding. 



The first task in crossing grapes is to remove the anthers 

 before the flower opens, a process known as emasculation. 

 This is necessary to prevent self-pollination. This first opera- 

 tion having been performed, the cluster of grape-flowers must 

 be tied securely in a bag to protect it from foreign pollen which 

 otherwise would surely be carried to the stigma by insects. 



