Excerpt from The Establishment of Varieties in Coleus by the Selection of Somatic Variations Judgment as to the genetic constitution of a plant is based on the expression of characters in a plant itself, in members of a selfed progeny and in a hybrid progeny. It is largely through the study of the last named that there has developed the conception that characters are represented in cells by unit factors. In considering the evidence as to whether these assumed factors are in any sense units, it is highly essential that the individual be studied as to the variability of characters and the range of expressions exhibited in homologous parts. For this purpose so-called bud variations are especially significant, since they represent, perhaps, the extreme of spontaneous somatic variability and suggest that quite as marked variations as exist in hybrid progeny may develop in the parts of a single individual. In an excellent summary of all cases of bud variation known to him, Darwin (1868) shows that the phenomenon is widely distributed in the plant kingdom and that it may affect various parts of a plant. He drew the highly interesting conclusions that they include: (1) reversions to characters not acquired by crossing, (2) reversions in hybrids to parental characters, and (3) cases of spontaneous variability. The latter he considered as of the same sort as appear in seed progeny. According to Darwin's views, "long-continued and high cultivation" are conditions that induce bud variations, but he recognized that certain cases, especially those when only single buds or parts of buds are changed, do not seem to be due to external conditions. Darwin considered in general that bud variations are evidences of the almost unlimited variability that plants manifest, due to the nature of living structures and the exciting causes of environment. Darwin did not believe in fixed hereditary units. He held that characters may respond directly to the effects of environment, and also exhibit spontaneous variability both in seed and in vegetative propagation. Furthermore, sexual hybridization was considered to be of influence in modifying and changing inherited characteristics. De Vries (1901, vol. i, p. 39) considers that bud variations are spontaneous changes most common in varieties with incompletely fixed characters. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.