270 CROSS IMPREGNATION. 



catkins, suspended over the former trees at the proper 

 season. Whether this effect, supposing it true, be 

 owing to the proper male flowers being expended 

 too soon, or from the incontinent appetite of the 

 females, is uncertain. Be this as it may, the phe- 

 nomenon is, however, very similar to what is often 

 seen to take place among breeding animals. 



Another advantage arises from cross-impregnation, 

 namely, making fine flowering exotics that are too 

 tender to bear the open air in Britain, more hardy. 

 If the tender female be dusted with the pollen of a 

 hardy male of the same genus, or vice versa, a variety 

 will be produced which will possess the beauty of the 

 one in a great degree, and the hardihood of the 

 other ; and by advancing to gain hardiness in one 

 direction, fine colour may be obtained by trying back. 

 If acclimatation be at all a practicable expedient, 

 cross-impregnation appears, from what has already 

 been accomplished, to be one of the most effectual 

 means. This opinion is founded on what has lately 

 been accomplished in crossing the Rhododendrum 

 arbbreum with the JR. ponticum ; an intermediate 

 variety has been obtained, partaking of the colours of 

 each somewhat blended, together with a great portion 

 of the hardiness of the R. ponticum. As species have 

 only a limited range of constitutional variation, we 

 know not how far such changes may be carried ; but 

 even this union between two reputed and distinct 

 species shows that our knowledge of the powers of 

 plants is not yet complete. 



