No. 443] MUTATION IX PLANTS. 765 



Ginotlicra nanc/la was taken by deVries to have a degree of 

 separation from the parent type that would lead it to be consid- 

 ered as a variety, a conclusion which is borne out by Dr. Small's 

 description as given below : 



I. Sccdlins^ about two months old. — Resembles that of (Jino- 

 t/iera linnarckiana ; but the leaf-blades are less uniform, some of 

 them ovate or oval, others ovate and somewhat lobed near the 

 apex, others broadly ovate, or prominently apiculate. 



II. Seedling § months old. — Nearly like that of Ui. lamarck- 

 iana\ but leaves inclined to have longer petioles. 



III. Adult plant. — Plant, stout and stocky in all [)arts, resem- 

 bling iK. lamarckiana, but smaller, less than 3 dm. tall. 

 Stem obscurely channeled, hirsute with somewhat ascending 

 hairs, simple: leaves approximate, 7-12, 5 cm. long near the 

 base of the stem ; blades shallowly, often rather remotely, but 

 quite evenly toothed, those of the lower cauline leaves spatulate 

 to oblong, acute, or acutish, each narrowed into a semi-terete 

 petiole, those of the upper cauline leaves broadly oblong to 

 oblong-ovate, acute or slightly acuminate, nearly sessile : bracts 

 subcordate at the base : hypanthium 3-3.5 cm. long, about 5 

 mm. wide at the mouth, obscurely ridged : sepals 3-3.5 cm. 

 long, longer than the tubular portion of the hypanthium, the 

 free tips 5-6 mm. long: petals 3.5-4 cm. long, emarginate : 

 anthers 11-12 mm. long: stigmas 4-5 mm. long. 



General Summary. 



Discontinuous variation as a possible method of origin of 

 species was considered by Charles Darwin in his studies of 

 plants and animals under domestication, and he concluded that 

 if new forms did arise in this way that they were not self-main- 

 tenant (1868). On the other hand Galton took the position that 

 the evolution of species is not necessarily by minute steps (1889), 

 but Dollo (according to deVries's, Mntationstheorie, Bd. i, p. 46, 

 1 901) was the first to accept discontinuous variation as the prev- 

 alent method of origin of species (1893). Bateson (1894) 

 brought together a large amount of evidence as to types which 

 have arisen in this manner, and a comprehensive summary of 



