FUNCTION,] WILD HYBRIDS. 243 



uncommon. Among the most remarkable cases are, the 

 Cistus Ledon, constantly produced between C. monspessulanus 

 and laurifolius; and Cistus longifolius, between C. mons- 

 pessulanus and populifolius ; in the wood of Fontfroide, near 

 Narbonne, mentioned by Bentham. The same acute botanist 

 ascertained that Saxifraga luteopurpurea of Lapey rouse, and 

 S. Ambigua of De Candolle, are only wild accidental hybrids 

 between S. aretioides and calyciflora : they are only found 

 where the two parents grow together ; but there they form a 

 suite of intermediate states between the two. Gentians, 

 having a similar origin, have also been remarked upon the 

 mountains of Europe ; and altogether about forty cases of 

 wild reputed species of the genera Ranunculus, Anemone, 

 Hypericum, Scleranthus, Drosera, Potentilla, Geum, Medi- 

 cago, Galium, Centaurea, Stachys, Rhinanthus, Digitalis, 

 Verbascum, Gentiana, Mentha, Quercus, Salix, and Narcissus, 

 have been collected by Schiede, Lasch, and De Candolle ; to 

 which far too many may be added from the works of species- 

 making botanists. It is impossible not to believe that a great 

 proportion of the reputed species of Rosa, Rubus, and other 

 intricate genera, have had a hybrid origin. 



Mr. Thwaites has made some very interesting remarks 

 upon the light which these mules throw upon the pheno- 

 mena of vegetable impregnation. 



" The most eminent physiologists," he observes, " seem to 

 be arriving at the opinion that the fertilisation of the ovule, 

 as it is termed, consists in the union of a part of the contents 

 of a pollen-grain with certain matter contained in the ovule, 

 and that the embryo originates from this mixed matter. The 

 correctness of this opinion is rendered still more probable by 

 the consideration of what takes place under the circumstances 

 of hybridisation of species. The phenomena which present 

 themselves in these cases are of the highest physiological 

 interest, and it seems impossible after a careful consideration 

 of them to doubt that the hybrid plant owes its existence to 

 consists in its earliest condition of an endochrome made up 

 of a portion of the endochrome of each of the parent plants ; 

 for the development of the hybrid embryo into the mature 



