Idio-plasm, Nägeli’s term, 31; A and B, 31-32; self-multiplication of, 34; amount of idio-plasm A in the nucleus, 40. Ids, 123. Individual differences, Weismann, 39, 41, 43. Influence of a previous sire upon the progeny of the same dam, _see_ Telegony. Influence of external conditions, _see_ Acquired characters. Influence of pollen upon somatic tissues, _see_ Xenia. Inheritance of acquired characters, _see_ Acquired characters. Invertebrates, Weismann on sexual apparatus of, 72, 74, 109. J. Jelly-fish, regeneration in, 4. =Jordan=, on inheritance of acquired characters in plants, 93. K. Karyokinesis, 37. L. =Lamarck=, Weismann and, 16, 21. Lamarckian factors, importance of, 57, 59, 62, 65, 67, 69, 82, 106-108, 111-112, 128, 147. Life, duration of, 7, 10. M. =Malingié-Nouel=, on Telegony, 193 _et seq._ Malva, Gärtner on, 80. =Maupas=, on the Protozoa, 101, 148. Metazoa and Metaphyta, cause of mortality of, 7, 24, 148; relation of progeny to parents in, 16; transmission of acquired characters in, 16; propagation in, 51. =Mivart=, on inheritance of acquired characters, 94. Molecules, 54, 123. =Morton, Earl of=, on Telegony, 192. =Müller, Fritz=, on bud-variation, 95. Multicellular organisms, _see_ Metazoa and Metaphyta. N. =Nägeli=, theory of heredity, 2; and idio-plasm, 31, 187; and germ-plasm, 36; on inheritance of acquired characters in plants, 93. Natural selection, the cause of death, 8; action of, 20; the material for the operation of, 13, 57; not the cause of sexual propagation, 13-14; and the Protozoa, 15, 101-102; and germ-plasm, 21; sole cause of organic evolution, 25, 59, 111, 114. =Nouel, Malingié=, on Telegony, 193 _et seq._ Nucleo-plasm, of germ and somatic cells, 30. Nucleus, alone contains germ-plasm, 29; contains two substances, 33; and heredity, 37; and polar bodies, 40; amount of idio-plasm A in, 40. Nutritive congenital changes, 64. O. Orchideae, Hildeband on, 80. Organic evolution, the cause of, 25; Weismann’s theory of, 26, 48, 50, 58, 66, 68, 87, 100, 104, 106-108, 114-115, 147. Ova, Weismann on the size of, 39. P. =Pallas=, on variability, 154. Pangenesis, Darwin’s theory of, 2, 26; and Weismann’s theory of, 52, 55, 71, 73, 121; and Panmixia, 59-60; Galton on, 60. Panmixia, and Pangenesis, 59-60. Parthenogenetic organisms, and natural selection, 15; no congenital variations in, 72, 75. Parthenogenetic ova, Weismann on, 45, 89, 91, 109. Phylogenesis, 34. Physiological isolation, of germ-cells, 74. Plants, reproductive cells of, 74; influence of pollen upon somatic tissues of (Xenia), 78-80; bud-variation in, 90, 94-99; Hoffmann’s investigations on the inheritance of acquired characters in, 93.