48o 



SENESCENCE AND REJUVENESCENCE 



281; of nervous system, 281, 297; of 

 flower, 375; in animal egg, 407. See 

 also Dedifferentiation; Differentiation; 

 Substratum. 

 Starfish: axial relations in, 200; axial gra- 

 dient in, 203; early death after matur- 

 ation of unfertilized egg of, 307, 405; 

 susceptibility of eggs of, 351, 413; 

 oxygen consumption in egg of, in rela- 

 tion to fertilization, 405, 414; condi- 

 tions of maturation in, 405; egg of, 

 almost parthenogenic, 405, 410; suc- 

 ceptibility during early development 

 of, 413; critical stage in development 



of, 413- 

 Star\^ation: in Planar ia dorotocephala, 

 35, 155, 156; reduction of nervous 

 svstem during, 35, 281; in other 

 p'lanarians, 44; decrease in cell size 

 during, 155; death from, 156; inCassjo- 

 pea, 163; capacity for acclimation 

 during, 165; effect of partial, 167, 

 280, 386; stunting effect of partial, in 

 mammals, 281; rejuvenescence in con- 

 nection with, in higher animals and 

 man, 298, 299; increase in weight 

 after, 298, 300; susceptibility of fishes 

 during, 299; senescence as a process 

 of cell, 437. See also Nutrition; 

 Reduction; Rejuvenescence. 

 Statoblasts of bryozoa, in relation to 



age cycle, 256, 259. 

 Stenostomum, agamic reproduction in, 

 133; increase of susceptibility during 

 agamic reproduction in, 135. 

 Stentor coeruleus: agamic reproduction 

 in, 138; rejuvenescence of, in agamic 

 reproduction, 141, 142. 

 Sternaspis scutata, oogenesis of, 341. 

 Strongylocentrotus lividus, increase in 

 oxygen consumption of, during early 

 development, 405. See also Sea-urchin. 

 Subordination, 215. 



Substratum: in relation to reaction, 19, 

 42; physiological stability of, 40, 41 > 

 50, 53, 183, 194, 227, 267, 298, 304, 

 460, 463; as metabolic sediment, 41; 

 Huxley's conception of, 41; function 

 in relation to, 42; selective action^ of 

 starvation upon, 44; changes in, during 

 development, 45, 5°, 1^35 embry- 

 onic cell as metabolic, 49; action of 

 narcotics on, 69, 70; in relation to 

 maintenance of axial gradients, 226. 

 See also Dedifferentiation; Differentia- 

 tion; Stability, physiological. 

 Summer egg, 390. 



Surface and volume: in relation to nar- 

 cotic action, 75, 78; in relation to 



metabolic rate, 272; in relation to 

 senescence, 437; significance of rela- 

 tion between, 438. 

 Susceptibility: to cyanides and narcotics, 

 66; in relation to metabolic rate, 66, 

 71, 72, 73, 79, 82; methods of use of, 

 73, 77, 82; in relation to carbon- 

 dioxide production, 73; in relation to 

 age in Planar ia maculata, 93; in 

 relation to age in Planaria doroto- 

 cephala, 99; in relation to age in 

 Planaria velata, loi; in relation to age 

 in other forms, loi; of pieces of 

 Planaria dorotocephala after section, 

 105; in relation to different degrees of 

 reconstitution, 113; increase of, in 

 agamic reproduction in Planaria doro- 

 tocephala and P. macidata, 127; increase 

 of, in agamic reproduction in Planaria 

 velata, 132; increase of, in agamic 

 reproduction in Stenostomum,^ 135; 

 increase of, in agamic reproduction in 

 oligochetes, 136; increase of, in agarnic 

 reproduction in infusoria, 141; in- 

 crease of, in agamic reproduction 

 in hydra, 146; increase of, in agamic 

 reproduction in Pennaria, 149, 151; 

 increase of, during starvation in 

 Planaria dorotocephala, 157; in rela- 

 tion to acclimation in starved Planaria 

 dorotocephala, 165; in relation to 

 axial gradients, 202; of _ dominant 

 region to external conditions, 226; 

 of fishes during starvation, 299; of 

 gametes of animals, 351; at time of 

 conjugation, 352, 381; of sexually 

 mature Planaria dorotocephala, 385; 

 of sexually mature Planaria macidata, 

 386; of different larval generations 

 in trematodes, 396; increase of, after 

 fertilization in animal eggs, 405, 406; 

 of different eggs to parthenogenic 

 agents, 410; of starfish during early 

 development, 413; of sea-urchin dur- 

 ing early development, 413; of Nereis 

 during early development, 414; of 

 Arenicola during early development, 

 415; of frog and salamander during 

 early development, 418. See also 

 Metabolic rate. 

 Symmetry, physiological: occurrence of, 

 201, 203; in'relation to axial gradients, 

 204. 



Tautogolabrus adspersus: susceptibility 

 of eggs of, 351: susceptibility during 

 early development of, 416, 417; period 

 of developmental rejuvenescence in, 

 compared with that in Fundultis, 

 417. 



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