478 



SENESCENCE AND REJUVENESCENCE 



period of developmental, in Tautogo- 

 labrus and Funduhis, 417; in relation 

 to segmentation in Nereis larva, 421; 

 in embryonic development of plants, 

 424; degree of, in agamic and gametic 

 reproduction, 425; by substitution of 

 gametic, for agamic reproduction, 426; 

 as a casting off of injurious substances, 

 435; Minot's theory of, 441; nucleo- 

 plasmic relation in, 441; as result of 

 increase in nucleoplasmic interchange, 

 444; in relation to colloid changes, 

 445; as a reversal of autocatalytic 

 reaction, 448; not a special process, 

 459; not necessarily a reversal of 

 senescence, 459; possibility of, in 

 evolution, 464; in non-living systems, 

 465. See also Dedifierentiation; 

 I\Ietabolic rate. 

 Reproduction, agamic: in Planar la doro- 

 toccphala, 122; resemblance of, to 

 reconstitution, 126, 132, 135, 140; re- 

 juvenescence in, 126, 141, 146, 149, 151, 

 181, 239, 252, 255; in Planaria vclala, 

 130; in Stenostomum, 133; in oligo- 

 chetes, 136; in infusoria, 137, 377, 379; 

 in hydra, 145; limit of dominance in, 

 220; in plants, 221, 231, 238; in rela- 

 tion to physiological isolation, 229; in 

 armadillo, 231; different forms of, in 

 plants, 239, 247; in relation to indi- 

 viduation in plants, 244; in gameto- 

 phyte of plants, 254, 366; various 

 forms of, in lower animals, 255; as 

 a result of senescence, 259; infre- 

 quency of, in higher animals, 268; 

 in production of gametophyte, 377; in 

 relation to conjugation, 377; in marge- 

 lid medusa, 384; degree of rejuvenes- 

 cence in gametic and, 425. See also, 

 Dedifferentiation; Reconstitution; Re- 

 juvenescence; Reproduction, gametic, 

 in general. 

 Reproduction, experimental: in Planaria 

 dorotocephala, 103, 105, 214, 222; 

 ditierent degrees of, in; in Tubularia, 

 210; continued, in plants, 239, 370. 

 See also Reconstitution; Rejuvenes- 

 cence; Reproduction, agamic. 

 Reproduction, gametic: absence of, 99, 

 130, 136, 239, 366, 369, 386, 387, 388; 

 rejuvenescence in, 186, 270; periodic, 

 192, 388; prevention of, by agamic 

 reproduction, 239, 367, 370; in relation 

 to senescence, 270, chap. xiv,_ 460; 

 parthenogenic and zygogenic, in inver- 

 tebrates, 389; degree of rejuvenescence 

 in agamic and, 425; Godlewski's com- 

 parison of, with regeneration, 427. 

 See also Conjugation; Fertilization; 



Gamete formation; Gametes; Par- 

 thenogenesis; Reproduction in general. 



Reproduction in general: as characteristic 

 of organism, i, 202; in relation to age 

 cycle, 178, 259; different processes of, 

 in plants, 238, 247; cycle of, in inver- 

 tebrates, 390; fundamental similarity 

 of all forms of, 427; as condition of 

 death and rejuvenescence, 433; defini- 

 tion of, 460; inheritance involved in all 

 cases of, 462. See also Reconstitution; 

 Rejuvenescence ; Reproduction, agamic, 

 experimental, gametic. 



Reproductive cycle: in daphnid Crus- 

 tacea, 390; repetition of, 392; in 

 rotifers, 392; in trematodes, 395. See 

 also Reproduction, agamic, experi- 

 mental, gametic, in general. 



Reversibility: of reaction, 38, 56, 67, 71; 

 of development, 56, 64, 155, 188; of 

 relative susceptibilities, 72, 82. 



Riccia, origin of gametes in, 318. 



Rotifers, parthenogenesis and zygo- 

 genesis in, 392. 



Saggita, germ path in, 328. 



Saprolegnia: spore formation in, 247; 

 conditions of spore formation in, 250; 

 gametes of, 316; conditions of gamete 

 formation in, 364. 



Sea-urchin: axial gradient in, 203; 

 temperature coefhcient of length of 

 life in eggs of, 308; susceptibility of 

 eggs of, 351; increase in metabolic 

 rate in eggs of, after fertilization, 405, 

 414; conditions of maturation in, 405; 

 oxygen consumption during early 

 development of, 4"; heat production 

 during early development of, 412; 

 susceptibility during early develop- 

 ment of, 41 2 ; critical stage in develop- 

 ment of, 413. 



Secretions, internal. See Correlation. 



Segmentation: in higher animals, 269; 

 in larva of Nereis, 421; in larva of 

 BranchipKS, 422. 



Segregation. See Gametes; Germ path; 

 Germ plasm. 



Self -differentiation: in general, 50, 55; 

 of apical region of Tubularia, 210; of 

 apical region of Planaria dorotocephala, 

 213. 



Sempervivum funkii, Klebs's experiments 

 on control of flowering in, 372. 



Senescence, evolutionary: occurrence of, 

 193, 464; paleontological evidence for, 

 193; in evolution of higher organisms, 

 464; control of, 465. 



