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LIU. Observations on Hybrids. By Thomas Andrew 

 Knight, Esq. F. R. S. $c. President. 



Read February 6th, 1821. 



Mu c h difference of opinion appears to exist between my 

 friend the Hon. William Herbert, and myself, relatively 

 to the production of Hybrid Plants, he supposing that many 

 originally distinct species are capable of breeding together, 

 without producing mules (that is, without producing plants 

 incapable of affording offspring), and I considering the fact 

 of two supposed species having bred together, without pro- 

 ducing mules, to be evidence of the original specific identity 

 of the two. Our difference of opinion is, however, I believe, 

 apparently much greater than it really is : for I readily con- 

 cede to Mr. Herbert, that great numbers, perhaps more 

 than half, of the species enumerated by botanical writers, 

 may be made to breed together, with greater or less degrees 

 of facility : but upon what sufficient evidence the originally 

 specific diversity of these rests, 1 have never been able to 

 obtain any thing like satisfactory information ; and I can- 

 not by any means admit, that plants ought to be considered 

 of originally distinct species, merely because they happen to 

 be found to have assumed somewhat different forms, or 

 colours, in an uncultivated state. The Genus Primus con- 

 tains the P. Armeniaca, P. Cerasus,P. domestica, P. insititia, 

 P. spinosa, P. Sibirica, and many others. Of these, I feel 

 perfectly confident, that no art will ever obtain offspring (not 



