JOHANNSEN, W. (WILHELM). - INTRODUCING "PURE LINES" IN GENETICS.

Ueber Erblichkeit in Populationen und in reinen Linien. Ein Beitrag zur Beleuchtung schwebender Selektionsfragen.

Jena, Gustav Fischer, 1903. Lex8vo. Fine contemp. hcloth., spine gilt and with gilt lettering. (6),68 pp., textfigs. Internally clean and fine.

First edition of a groundbreaking work in genetics in which Johannsen introduces the concept of "pure line". Johannsen's work is dedicated to Francis Galton, "the creator of the exact science of heredity". Johannsen was the first to attribute to mutation the origin of the small differences in the continous kind of variability characteristic of normal heredity.

"Yet Johannsen had shown that Galton's "law of regression" was wrong when applied as Galton had done - to impure or mixed populations. He proved that selection was ineffective - that is, regression to parental averages was complete - only in the offspring derived by self-fertilization from a single parent, as in peas, beans, and other "selfers." The offspings and descendants from such a plant Johannsen referred to as a "pure line". His theory was that offspring of a pure line were genetically identical and that fluctuating variability among such offspring was due to effects of change and enviromental factors. These effects were not heritable and hence were not subject to the action of selection, either natural or artificial."(DSB VII, p. 114).

Garrison & Morton No. 242.

Order-nr.: 44335