Author: Weismann, A. [F. L.]
Title: Die Entstehung der Sexualzellen bei den Hydromedusen. Zugleich ein Beitrag zur Kenntniss des Baues und der Lebenserscheinungen dieser Gruppe.
Description: Jena, Gustav Fischer, 1883. In two volumes (text and atlas). 4to (35.4 x 27.2 cm). Title page, iii- xiii, 295 pp. (text volume); Title page, [i] p.; 24 chromolithographed plates with explanatory text leaves (atlas volume). = August Friedrich Leopold Weismann (1834-1914) was a German evolutionary biologist, who was ranked by the great 20th-century evolutionary biologist Ernst Mayr (1904-2005) as the second most notable evolutionary theorist of the 19th century, after Charles Darwin. This is his rarely seen seminal work on the development of sexual cells in invertebrates, in particular medusae on which he based his Germ-Plasm theory, a "...concept of the physical basis of heredity expressed by the 19th-century biologist August Weismann. According to his theory, germ plasm, which is independent from all other cells of the body (somatoplasm), is the essential element of germ cells (eggs and sperm) and is the hereditary material that is passed from generation to generation. Weismann first proposed this theory in 1883" (Brittanica). "He ... took up the examination of the Hydrozoa and followed the origin of the cells through generations of Hydromedusae. The culmination of this work was Die Entstehung der Sexualzellen bei den Hydromedusen (Jena, 1883), and his conclusions, as he traced the fate of primitive germ cells and those after them, were strong evidence to Weismann that there was a continuity of the germ plasm" (DSB). Slight staining to the wrappers of the atlas, text rear wrapper somewhat frayed, a few, isolated spots, but generally very clean, including the fine plates. A very good copy. Cat. BM(NH) p. 2287; DSB XIV, p. 234; Nissen ZBI, 4361.

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