1899.] NATURAL SCIENCES OF PHILADELnilA. 91 



nearly identical in character as they grew. The branches were 

 islender, smooth, with scattered spines, and no aciculse. As the 

 plants gained vigor, strong branches, densely clothed with bristles, 

 would appear from the rugom plants, and ultimately became abso- 

 lutely that species. Some of them would, however, continue to 

 produce some smooth slender branches; and these, flowering, were 

 purely Rosa cinnamomea — the two species flowering on the same 

 plant. These separate blocks of roses are still blooming Avhere 

 they were sown, and in the bed of Rosa rugosa there are ten plants 

 that still continue Rosa cinnamomea. 



The bed of Rosa cinnamomea continued its comparatively weak 

 growth characteristic of the species. Occasionally a strong shoot 

 would push out from near the ground covered with bristles as in 

 R. rugosa; but it would eventually weaken, become smooth, and 

 have the smaller flowers, foliage, and, in fact, be nothing but R. 

 cinnamoynea. One only assumed a more vigorous and bristly 

 character. This plant has the flowers as large as those of R. 

 rugosa — that is to say, they are more than double the size of the 

 normal cinnamon rose, though continuing the pale rose color 

 instead of the deep crimson of R. rugosa. The foliage also, 

 though not as coarsely wrinkled, that is to say, rugose, as the 

 other, still is diverse from the type, and is an advance in the 

 direction of the latter rose. 



Two remarkable facts are made clear by these observations: 



First. — Two totally distinct forms can be produced from the 

 same seed vessel, though every condition surrounding their incep- 

 tion seems exactly the same. 



Second. — Rosa rugosa, a species with characters markedly distinct 

 from Rosa cinnamomea, is nevertheless an evolution fi'om that 

 species, and has been 2:)roduced by the energy of a more vigorous 

 development. 



We may conclude from these facts that however much may be 

 ■conceded to gradual modifications extending over indefinite periods 

 as an agency in the evolution of species, development need not be 

 dependent on this principle alone. The varying degrees of inter- 

 nal energy must be credited with producing sudden and remarkable 

 changes, though we may not yet be able to perceive clearly the 

 nature of the motive power that induces it. 



