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XXXIX. An Account of some Mule Plants. By Thomas 

 Andrew Knight, Esq. F.R.S.fyc. President. 



Read May 6, 1823. 



XVe excessive rarity of Mule Plants, in a perfectly wild 

 state, ( if in such they exist at all), and the facility with which 

 they are, in many cases, obtained in the garden, seem to 

 countenance the opinion, which is entertained by many bota- 

 nists, that plants of different species do not readily breed 

 with each other, till their natural habits have been broken 

 and changed by the operation of culture through some suc- 

 cessive generations. Vegetable mules are, however, never 

 produced except under circumstances which rarely, if ever, 

 occur in a perfectly natural state ; for experiment has satis- 

 fied me, that not only the pollen of the alien species must be 

 introduced at the proper period, but also, that the natural 

 pollen must be kept away not only at that precise period, 

 but generally, for several succeeding days afterwards : also, 

 and even under the most favourable circumstances, I have 

 never succeeded in obtaining mules, unless the plant or a 

 considerable branch of a fruit tree, has been reduced to the 

 necessity of nourishing mule offspring, or none. When the 

 later blossoms on a fruit tree were suffered to remain, such 

 branch either threw off the fruit which would have afforded 

 mule plants, or the natural pollen was found to have been 

 subsequently introduced by insects, or winds, and to have 



