Since the Primus species was originated, numerous similar cases have attracted attention, such as my now popular Phenomenal produced by crossing the Cuthbert raspberry with our native Pacific coast blackberry, and the Logan berry, both of which, though a complete blend of two such distinct species, yet reproduce from seed as truly as any wild rubus species.
I have had also growing on my grounds for some fifteen years or more hybrids of Rubus idæus and Rubus villosus, both red and yellow varieties. All are exactly intermediate between these two very widely different species, yet both always come true intermediates from seed, generation after generation, never reverting either way.
By crossing the great African "stubble berry" (Solanum guinense) with our Pacific coast "rabbit weed" (Solanum villosum) an absolutely new species has also been produced, the fruit of which resembles in almost every particular the common blueberry (Vaccinium Pennsylvanicum), and while the fruit of neither parent species is edible, the fruit of the newly created one is most delicious and most abundantly produced, and the seedlings, generation after generation though produced by the million, still, all come as true to the new type as do either parent species to their normal type.
Still another example of this mode may be found in my experiments with opuntias. By crossing O. tuna with O. vulgaris, thousands of seedlings have been produced, all of which, in the first, second and third generations, though a well-balanced blend of the two natural species, still come as true to the newly created species as do either parent species to their own natural types.
Not only does this new mode hold true under cultivation but species are also summarily produced in a wild state by natural crossing.
The western blackcap (Rubus occidentalis) and the eastern red raspberry (Rubus strigosus) when growing contiguous, as they very commonly do in Central British America, often cross, forming an intermediate new species which sometimes sorely crowds both of the parent species, and when brought under cultivation still firmly maintains its intermediate characters, no matter how often reproduced from seed. And still further, our common "tarweed" (Madia elegans) with its beautiful large blossoms often crosses with M. saliva with its insignificant pale yellow flowers, producing a complete intermediate. I have not yet determined whether the intermediate will reproduce true from seed, but confidently expect it to do so. Similar results among wild evergreens and deciduous trees and shrubs and herbaceous plants have been frequently and forcefully brought to my attention, leaving little doubt in my own mind that the evolution of species is by more modes than some are inclined to admit.
