INDEX 



463 



pH, 



bicarbonate, relation to, 361 

 changes in, microenvironment, 338 

 control of, method for, 351, 353 

 equilibrium with pCO- and bicarbon- 

 ate, 361 

 microinethod for, 345 

 pCOo, relation to, 361 

 on regeneration, 405 

 sexual differentiation, importance in, 



350 

 on systems other than hydra, 354 

 Pharmacological compounds, in coelen- 



terates, 179-186 

 Photosynthesis of zooxanthellac, on cal- 

 cification, 271-273, 277, 280, 281 

 Phijsalia, 169-178 

 captivity of, 178 

 feeding reflex of, 226 

 fishing tentacle of, 169-171 

 gastrovascular activity of, 174 

 gastrovascular fluids, composition of, 



176 

 nematocysts, 



battery of, 169 



discharge of, 171 



distribution of, 169 



isolation of, 171 



origin of, 175 



purification of, 172 



toxin of, 173 



transport of, 176 

 toxin of, 169 



action of, 178 



amino acids of, 173 



bioassay of, 173 



origin of, 173, 175 



peptides of, 173 

 Physiological differences, among hvdroids, 



371 

 Pigments of hydra, 440 

 Planaria, regeneration, lipoic acid on, 



410 

 Planuloid buds, 



see also Frustule, 318 

 Plasma membrane, 54, 56 



joined by septa, 58 

 Plumularians, growth zone of, 300 

 pO. 



control of, method for, 351, 353 

 microenvironment, changes in, 338 

 micromethod for, 344, 345 

 sexual differentiation, effect on, 347, 



348 

 on systems other than hydra, 354 



Podoconjne, 356 



Polyp, of Craspedacitsta, 317 



capitulum of, 317 



regions of, 317 



shape of, 317 



size of, 317 

 pNHo, 



gradient of, 358 



mediod for controlling, 351, 353 



microenvironment, changes in, 338 



micromethod for, 344, 345 



on sexual differentiation, hydra, 349 



on systems other than hydra, 354 

 Population density, influence on halo 



zone, 340 

 Proline, 



activates feeding reflex of Cordijlo- 

 phora, 226 



component of nematocvst capsule, 148, 

 154 

 Protease, 



activate feeding reflex, 

 of hydra, 224, 225 

 of CordyJoptiora, 226 



of hydra, 241 

 Protein, 



distribution of, in budding hydra, 441- 

 448 



of toxins, 180 

 Protein reserve droplets, 326 

 Purified inhibitor, 



see Inhibitor, of succinoxidase activity 



Quaternary ammonium compounds, 180 

 occurrence of, 185 

 paralyzing action of, 181 

 see also Tetramine 



Races, of H. litt oralis, 368, 371 



Rachevsky, fornmlation of cellular gra- 

 dients, 339, 340, 354 



Radiation, 



on aging, 390, 391 



on Campantdaria, 312, 390, 391, 395 



on differentiation. 390 



Receptor, 



affinity for glutathione, 218 

 analogy to enzymes, 217-219 

 combination with glutathione, 215, 216, 



218 

 half -saturation of, 218 

 location of, 229 

 saturation of, 217 



