CH. VI.] THE FLOWER. QOl 



plants may or may not be brought into fertile union 

 through intermediate crosses. A very short time ago 

 the azalea and rhododendron were thought incapable 

 of such union, but this opinion is now exploded, for 

 rhododendron ponticum has been fertilized with the 

 pollen of azalea sinensis, and the progeny, between 

 that evergreen and this deciduous shiiib, is the pre- 

 viously unknown phenomenon a yellow rhododendron. 

 Though such unions may be effected, I entirely agree 

 with Mr. Knight in anticipating that the progeny will 

 be mules, incapable of producing offspring. Jt is 

 quite time that many plants, said by botanists to be 

 distinct species, have between them produced fertile 

 seeds, but I incline decidedly to the opinion, that this 

 fact demonstrates that they are not distinct species, but 

 only deviations from a common origin. For example, 

 the peach and almond are considered distinct species 

 by botanists, yet the fruit of both and of the nectarine 

 have been borne spontaneously by the same tree. " I 

 cannot," says Mr. Knight, " 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 Prmius contains the 

 P. ai'meniaca, 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 being mules) between the Pnuius 



