(5 HISTORICAL SKETCH. 



nott : for I cannot suppose that they believed the plants to 

 be hybrids between R. Ido&us and R. saxatilis. It is admit- 

 ted by zoologists that hybrids are of exceedingly rare oc- 

 currence when animals are left to their natural instincts, 

 although they are not unfrequent between domesticated 

 species : also, that it is in the higliest degree doubtful if a 

 really hybrid race exists even in domestication. Is it likely 

 that less care would be taken to keep the species of plants 

 free from intermixture than is believed to have been exer- 

 cised in the animal kingdom? Certainly a few fertile hy- 

 brids have been obtained artificially, but all the experiments, 

 accounts of which have fallen in my way, tend to show- 

 that even if isolated they revert to one or other of the pa- 

 rent species in a few generations. As Fries has more than 

 once remarked, to affix the stigma of hybridity is a conve- 

 nient mode of escape from many difficulties, but it is not 

 therefore the more likely to be just. "Ad hybriditatum 

 voluptas trahit omnes, (1) qui de specierum limitibus dubii 

 rem absolutam fiugunt : *videtur hybrida planta;' (2) qui 

 omnes recentius distinctas species ex arbitrio delere student : 

 'est hybrida forsan planta;' (3) quibus pravas ut species 

 tueantur, necesse est manifestos transitus ' pro hybridis for- 

 mis' declarare. At cum hybridas suas species haud limitare 

 valent, ulterius hybriditates hybriditatum tertii, c. s. p. gra- 

 dus urgent" {Fries Sy7nholce ad Historiarn Hieraciarum, 

 p.xxxil). In the eighth edition of the British Flora, the 

 authors state their belief that the British fruticose species 

 "might be advantageously reduced to five... which five 

 would then accord with the four sections into which Mr 

 Babington has now divided the group." 



In the above-mentioned editions (2nd and 3rd) of 

 Hooker's British Flora, Borrer adds only two to the sjDccies 



