THE GENUS ROSA 269 



unassailable, and occurs in regions so far asunder as to place 

 the original crossing, explanatory of the present segregation 

 of the type, far back in Miocene and Pliocene times. Thus 

 the hybridity, the existence of which we have almost certainly 

 proved, whilst capable of explaining some of the peculiarities 

 of the persistent species-type, cannot account for all. The 

 species-type idea is absolutely independent of hybridity, 

 although that phenomenon may tend to its perpetuation. 



Hidden hybrids as the roses would seem, some at least are to 

 be reckoned within the ranks of those classified under normal 

 conditions as true-breeding. Excluding proved apomictical 

 forms, Rosa omissa, R. mollis^ R. vinacea, R. flexibilis, 

 R. Linto7u, R.frutetonim, R. pvnpinellifolia and R. rugosa have 

 all been shown to reproduce their kind with reasonable fidelity 

 within the permissible limits of fluctuating variation known 

 for the group — an observation which, regarded in the light 

 of the behavour of Burbank's many " compounds," cannot 

 exclude their basal hybridity. 



Granting then that hybridity such as postulated here is 

 rampant throughout the Rosa;, they seem to me to afford exceed- 

 ingly unsafe material upon which to erect any fundamental 

 theory in genetics ; so, therefore, would the Epilobia which 

 are in exactly the same critical state, as a very casual 

 examination of a specimen of Epilobium hirsuttem will show. 

 An extension of the argument to the related Oenothera, which 

 produces a similar wealth of allied species in America, and 

 likewise displays bad pollen to a considerable degree, becomes 

 then quite natural. Inevitably, we are bound to take up the 

 position that, in all probability, the phenomena studied with 

 such detail in Oenothera Laniaixkiana, instead of being those 

 of mutation, are rather those of hybridity, and the elaborate 

 structure erected on them falls to the ground — a conclusion 

 likewise drawn from other considerations during experimental 

 work in Lepidoptera. 



Pollination in the Rosce. 



Investigating as I was the possible effect of cross- 



