INDEX 



NOTE References give the number of the page on which the matter 

 referred to begins. 



Acceleration, differential, 37 



Acclimation: in relation to physio- 

 logical condition, 31; differen-" 

 tial, 36 



Adjuster: as part of reflex arc, 

 233; adaptive function of, 237; 

 localization of, 249. See also 

 Arcs, reflex 



"All-or-none" law. See Excita- 

 tion; Transmission 



Amoeba, physiological gradients in, 

 86 



Amphibia: physiological gradients 

 in, 33 ; circulation in ovarian egg 

 of, 56; susceptibility in early 

 development of, 135 



Annelids: susceptibility in, 34; 

 electrical gradient in, 45 ; origin 

 of segments in, 132; centraliza- 

 tion in, 146; physiological domi- 

 nance in, 249. See also Segmen- 

 tation 



Anteroposterior development, law 

 of, 28 



Arcs, excitation : definition of , 236; 

 different degrees of develop- 

 ment of, in same individual, 

 242; functional axiation in, 242, 

 245; structural axiation in, 247. 

 See also Excitation; Transmis- 

 sion 



Arcs, reflex; functional irreversi- 

 bility of, 229; constitution of, 

 233, 248, 249; adaptive charac- 

 ter of, 233, 236; in relation to 

 excitation gradients, 234; views 

 concerning evolution of, 237; 

 in relation to neuro-muscle cell, 

 240; functional direction of, in 

 annelids, 249; postcephalic, in 



higher animals, 251; in amphib- 

 ian development, 252; spinal 

 paths of, in higher vertebrates, 

 259. See also Arcs, excitation; 

 Gradients, excitation. 



Axon, chaps, x, xi. 



Begonia, gradients in adventitious 

 buds of, 53 



Bryopsis, determination of polarity 

 by light in, 51 



Cassiopea, transmission in, 225, 

 246 



Centralization, nervous; defini- 

 tion of, 142; in relation to or- 

 ganismic pattern, 144; charac- 

 teristic of all nervous systems, 

 144; evolutionary changes in, 

 146, 153 



Cephalization, nervous, definition 

 of, 142. See also Centralization 



Cerianthus, axial integation in, 



248 



Conduction, 207. See also Trans- 

 mission 



Conductor: as part of reflex arc, 

 233; in primitive gradient, 234. 

 See also Excitation ; Transmission 



Correlation, chemical : significance 

 of, 10, 12, 13; nature of, 13; in 

 relation to organismic pattern, 

 14; in relation to external fac- 

 tors, 14; in relation to differen- 

 tiation, 93; in relation to origin 

 of nervous system, 107 



Correlation, contactual, 12 



Correlation, dynamic, 15. See also 

 Transmission 



Correlation, mechanical, 12 



291 



