220 



Index. 



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, 



5 2 .> 55) 7 T > 73» I21 ! and Pan- 

 mixia, 59-60 ; Galton on, 60. 



Panmixia, and Pangenesis, 59-60. 



Parthenogenetic organisms, and 

 natural selection, 15 ; no con- 

 genital 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 so- 

 matic tissues of (Xenial, 78-80; 

 bud-variation in, 90, 94-99 ; 

 Hoffmann's investigations on 

 the inheritance of acquired char- 

 acters in, 93. 



Polar bodies, Weismann on, 40, 

 46, 125 ; examination of Weis- 

 mann's explanation of, 42 ; 

 O. Hertwig on, 46, 125. 



Protophyta, natural selection and, 

 114. 



Protozoa, immortality of, 7 ; and 

 natural selection, 15, 114; 

 origin of species of, 15, 102 ; 

 action of environment on, 15; 

 Maupas on, 101. 



R. 



Regeneration, in sea-anemones and 

 jelly-fish, 4, 35 ; of an entire 

 organism, 34 ; Weismann on, 

 51 et seq. ; in Begonia, 5 2 ; 

 Rev. G. Henslow on, 53 ; and 

 stirp, 59. 



Rejuvenescence, 166. 



Representative congenital changes, 



65. 



Reproduction, essential meaning 



of sexual, 8, 11 ; in the Pro- 

 tozoa, 16 ; somatic. 35. 



Reproductive elements, potential 

 immortality of, 9 ; of Vertebrates 

 and Plants, 74. 



Reversion, 3, 91, 105. 



Eoux, on the principle of " strug- 

 gle," 139- 



Sea-anemones, regeneration in, 4. 



Sexual apparatus of Invertebrates. 

 Weismann on, 72, 74. 



Sexual-cells and somatic-cells, 75- 

 77, 81, 84. 



Sexual propagation, essential 

 meaning of, 8, 11, 87; sole 

 cause of congenital variations, 

 12,89-90, 102, T35, 141, 153, 

 158; did not arise through the 

 agency of natural selection, 13- 

 14 ; in multicellular organisms, 

 51 ; Galton on the origin of, 

 103 ; in Cytisus adami, 127. 



Significance of sexual reproduction, 

 see Sexual Reproduction. 



Somatic-cells, nucleo-plasm of, 30; 

 and sexual-cells, 75-77,81,84. 



Somatic-idio-plasm, 32-33 ; and 

 germ-plasm, 69. 



Somatic reproduction, 35, 52. 



Somato-plasm and germ-plasm, 

 29. 



Specialized congenital changes, 65. 



Species, Weismann on the origin of 

 new, 100— iot. 



Spencer, Herbert, theory of 

 heredity, 2 ; on Telegony, 191 

 et seq. 



Stability of germ-plasm, see Germ- 

 plasm. 



Stirp, and gemmules, 58-59, 61 ; 

 and somatic tissues, 60 ; and the 

 germinal cells of Hydromedusae, 

 73; and germ-plasm, 75, 92, 

 106, 133. 



Strasburger, on Weismann's 

 theory of heredity, 51 ; on the 

 origin of sexual propagation, 

 167. 

 Stylonichza, Maupas on, 101. 



Summary, 103. 



