168 BOARD- OF AGRICULTURE. 



hybridizing. You have learned from President Chadbourne 

 in what way varieties are improved : in hybridizing you secure 

 a marked tendency to the production of varieties, some of 

 which you can turn to account. 



In presenting the views of Professor Nageli, and in com- 

 menting upon them, I have endeavored to put you in posses- 

 sion of the more important facts representing artificial hybri- 

 dization, and I have also sought to keep from encroaching 

 upon disputed ground. The general theory of hybrids, and 

 the interesting allied subjects of derivative hybrids and 

 graft-hybrids, cannot now be entered upon, but must be left 

 wholly imtouched. It only remains for me to urge you to 

 venture upon experiments in this field. A few in this au- 

 dience have already accomplished much. The history of the 

 improved varieties of corn and potatoes shows you that much 

 has been done : the excellent results indicate that there is 

 great encouragement for the future. Remember that the 

 requisites to success in such an undertaking are the follow- 

 ing, — knowledge of the plants with which you work, a 

 familiarity with what has already been done with the same 

 species, skill in your manipulation of the pollen and in other 

 details of practice, and, lastly, a good heart against the dis- 

 couragements which will meet you at the outset. Even a 

 cursory examination of the subject will convince you that 

 here lies before you, as practical men, a broad and inviting 

 field of profitable labor. 



A. The cases in which hybrids have been produced between genera 

 are given by Niigeli (p. 399 of his work) as follows : — 



Lychnis and Silene. 



Rhododendron and Azalea. 



Rhododendron and Rhodora. 



Rhodora and Azalea. 



Rhododendron and Kalmia. 



Rhododendron and Menziesia, 



jEgilops and Triticum. 



The genera of Cactacece. 



The genera of Gesneriacece. 



Of those above mentioned the following have been recently placed by 

 Bentham and Hooker in a single genus, — Rhododendron, Azalea, and 

 Rhodora. 



To these genera may be added the case in which orchids have been 

 crossed, Calanthe and Limatodes in the production of Calanthe Veitchii. 



