296 



INDEX 



Summation, in reflex arc, 229 



Susceptibility: agents used in 

 determining, 29; non-specific 

 relation of, to physiological con- 

 dition, 30, 36,40; gradients in, 32; 

 changes in, during development, 

 33; specific, 34; of Planaria 

 dorotocephala, 34; modification 

 of development through differ- 

 ential, 36; method of measur- 

 ing, not exact, 38; in relation to 

 permeability, 41; of embryonic 

 heart, 48, 221; of alimentary 

 tract, 48; of ctenophore plate 

 row, 216; gradient in axon, 227; 

 of excitation mechanism, 228 



Symmetry: similarities of, in 

 plants and animals, 2; radial 

 and bilateral, 8, 25; spherical, 23; 

 physiological gradients in bilat- 

 eral, 28; as susceptibility gradi- 

 ents, 33; bilateral, in siphono- 

 phores, 33; origin of, 56; in 

 relation to differentiation in 

 general, 96; in relation to nerv- 

 ous structure, no, 149; bilat- 

 eral, in relation to dorsiventral- 



ity, 150. See also Pattern, 

 bilateral; Pattern, cell; Pattern, 

 organismic; Pattern, radiate 



Synapse: morphological character 

 of, 155; function of, 228 



Transmission: in physiological 

 correlation, 15; with decrement, 

 67, 69, 75, 77, 81, 208, 218, 223, 

 229; without decrement, 68, 75, 

 81, 99, ^208, 223_, 225, 246; 

 in primitive excitation pro- 

 cesses, 77, 207, 224; up and 

 down gradients, 97, 99, 211, 218, 

 224, 232, 249; conduction as 

 specialized, 207; in ciliated epi- 

 thelia, 209; in ctenophore plate 

 row, 212; reversal in direction 

 of, 217, 221; differences in rate 

 of, 219; in relation to synapse, 

 229; functional irreversibility in 

 direction of interneuronic, 229; 

 in dendrite, 231 



Tubularia, physiological independ- 

 ence of apical region in, 123 



Vitalistic theory, 7, 9 



