422 



ANIMAL AGGREGATIONS 



Hay infusion protects Procerodes from 



hypotonic sea- water, 228 

 Hayes, F. A., 282 

 HCI, effect on male development in 



Bonellia, 293 

 HCN, mass protection against, 237, 239 

 Headlee, T. J., 359 

 Heaton, T. B., 106, 118, 153 

 Hebard, M., 331 

 Hegel, vii 

 Hegner, R. W., 3^ 

 Helopeltis (tea bug), host for nematodes, 



300 

 Hempelmann, F., 70 

 Henking, H., 266 



Henrici, A. T., 103, 104, 105, 106, 247, 251 

 Hens, crowding affects rate of egg-laying, 



126 

 seasonal values, 129 

 flock organization, 1 29, 344 

 Herbst, C, 293 

 Herds, 12, 13, 27, 30, 34, 35, 339, 341, 348, 



353 

 Hermit crabs, 123, 296, 298 

 Hess, W. N., 90, 92 

 Hesse, R., 117 

 Heterotj^ic crowding in tissue cultures, 



151, 157 

 protection, against colloidal silver, 210, 

 231 

 against hypotonic sea- water, 228 

 in bacteria, 256, 259 

 in yeast, 259 

 excretory products and male produc- 

 tion in Cladocera, 305 

 Heterotypic flocks of birds, 28, 30, 79, 

 339, 342 

 see also Birds, flocking behavior 



Hibernation, 66, 70, 341 



temperature of bee cluster, 70 

 Hill, R. B, 13s 

 Hine, J. S., 75 



Hinrichs, M., 218, 219, 220, 265, 266 

 Hippodamla (beetle) abundance, 359 

 Hoffbauer, C, 115 

 Hogg, J., 108, no, 112, 118 

 Hogs, wild, mixed families, 27, 28 

 Holmes, S. J., 42, 89 

 Holmquist, A. M., 70, 71, 79 

 Hookworm, crowding affects rate of re- 

 production, 135 



Horde life in anthropoids, 347, 349, 350 

 Hormone, wound or division of Haber- 

 landt, 151 

 effect on sex in freemartin, 295 

 Houseflies, 359 

 Howard, H. E., 345 

 Howard, L. O., 359 

 Howell, A. B., 79, 80 

 Huxley, J., 213 



Hybridization, phase theory of locusts 

 and, 329 

 ratios affected by crowding, 331 

 Hydra, 17, 24, 358 



effect of crowding on growth, 112 

 mass protection from colloidal silver, 

 204 

 Ilydraclinia, polymorphism, 23 



relation to hermit crab, 29 

 H ion, effect on electrical charge of 

 spermatozoa, 278 

 see pH 

 Hydrogen peroxide, mass protection of 



bacteria against, 260 

 H2SO4, effect on male production in 



Cladocera, 306 

 Hydroides, distance sperm travel, 289 

 Hydroids, cell aggregations, 45 

 Hydrozoan colonies, 23, 353 



growing on crabs, 32 

 Hyman, L. H., 186 

 Hymenorus (beetle) abundance, 359 

 Hypotonic sea-water, protection from 

 222, 306, 357 

 method of measuring hj^aotonicity, 



224, 225 

 heterotj^ic protection, 228 

 factors contributing to, 231 



Ihering, H. von, 72 

 Indian tree swift, 12 



Individual, metazoan compared with a 

 bacterial colony, 261 

 with society, 353 



Infusion, protozoan, sequence of forms, 

 107 



Irvfusoria, see Protozoa 



Insects (general), migrating swarms, 34, 



317, 341 

 societies, 36, 338, 349, 353, 360, 362 

 "sleep" aggregations, 74 

 density of population and insect sur- 

 vival, 236 



