stimulus (Cimtiiiucil) 

 as activator of inherited behavior 



patterns, 13 

 as causing motile mtertidal 



species to move into proper 



zones, 362-363 

 internal, derivation of, 13-14 

 prefixes employed m identifying 



kind to which organisms 



respond, 12 

 receipt of as always causing 



definite action, 251 

 receptors for receiving of, 13 

 role of in conditioning, 15 

 sign, as trigger only for particular 



actions, 14 

 to migration of birds, 158 

 "trial and error" responses to, 



13 

 Stream(s) (see also Biocies, Stream; 



Rivers): 

 adjustments to current of: 

 by clinging mechanisms, 44-47 

 by swimming, 47-50 

 through avoidance, 47 

 altitude of and organisms in, 52- 



53 

 amount of food consumed by fish 



in, 55 

 amounts of dissolved solids in 



from runoff of falling rain, 65 

 and creation of flood-plain, 113 

 as differing from lakes, 59 

 biomass of, and fertility and chem- 

 ical composition of water, 56 

 carnivorous species in, 55 

 changes in shape and size of 



organisms in, 53 

 character of bottom of, 42-43 

 chemical analysis of to determine 



pollution, 57 

 comparative biomasses in kinds 



of, 55 

 deposition of alluvial soils by, 172 

 erosion of, 56-57 

 filter feeding in, 55 

 formation of beaver meadows in, 



172 

 formation of mud-bottom ponds 



in, 43 

 formation of through erosion of 



headwaters of, 42 

 headwaters of as poor habitat, 52 

 herbivorous species in, 55 

 impermanence of headwaters of, 



42 

 industrial pollution of, 57 

 introduction of fish into which did 



not occur there originally, 58 

 introduction of invertebrate 



animals into to determine 



pollution, 57 

 life- histories of insects of, 53-54 



Stream(s) (Conliiiiic(t) 

 major food substances in for 



stream animals, 54-55 

 material in suspension in, 52 

 measurement of primary produc- 

 tivity in, 204 

 organic pollution of, 57 

 organisms in and temperature, 



52-53 

 orientation behavior patterns of 



animals in, 50 

 oxygen content of, 51 

 passive conveyance of eggs and 



spores in, 146 

 population densities in, 55-56 

 principal habitats in, 42-43 

 problems in measuring productivity 



values in, 206 

 repopulation of, in fish management, 



58 

 respiratory equipment of animals 



in, 51-52 

 responses to bottom of: 

 burrowing, 51 

 placement of eggs, 51 

 segregation, 50 

 support and locomotion, 50-51 

 salt content of, 43 

 silting in, 56 

 size of, relation to distribution of 



species, 52 

 stages in aging of, 43 

 temperatures of, 43 

 variation of insect population in 



with season, 55 

 velocity of current in, 42-43 

 Strip Censuses: 

 inaccuracies in, 31-32 

 method for taking, 31-32, 32 

 Subsere(s): 

 burns: 

 animals in destroyed coniferous 



forest, 119 

 kinds of trees which invade 

 destroyed coniferous forest, 

 117-119 

 of longleaf pine, 117 

 function of as forest- edge in North 



American boreal forests, 306 

 in abandoned fields: 

 bird succession in, 115 

 stages in on Great Plains, 115 

 stages of in Atlantic and Gulf 



States, 115 

 stages of in Michigan, 115-116 

 stages in prarie region of 



Oklahoma, 115 

 succession in retarded by feeding 



animals, 115 

 succession rapid in, 115 

 in pasture: 

 native vegetation as eliminator of 

 domestic animal grazing, 116-117 



Subsere(s) (Coiilitiiiert) 

 overgrazing as factor in, 117 

 resistance of other species by 

 sod in, 116-117 

 role of fires in creating, 117 

 Succession {see also Seres; Sub- 

 seres): 

 and changing of lake types, 64-65 

 biotic: 

 convergence in, 22-23 

 disappearance of old species in, 



21 

 growth and dispersal rates as 



contributing factors to, 21 

 influenced by propagules available 



in area, 21-22 

 in terrestrial communities, 21 

 role of bioseres in, 22-23 

 changes in species composition 

 with increase of fertility during, 

 207 

 climatic: 

 as causing changes of bogs into 



marshes, 92 

 changes in environment as cause 



of, 23-24 

 in eastern North America due to 

 retreat of continental glacier, 

 23-24 

 climax stage in, 26 

 in arid climates, 120 

 true nature of for tundra regions 

 unknown, 316 

 early studies in, 5 

 forest- edge character of grassland 



vegetation during, 120 

 from sea to fresh water: 

 and brackish water species, 368 

 and fish migrating between fresh 

 and salt water for spawning, 

 368-370 

 and impoverishment of marine 

 species in approaching fresh 

 water, 368 

 and spawning of eels, 370 

 through gradual change from 

 salt water to fresh water, 368 

 from sea to land: 

 and development of mangroves 



in tropical regions, 368 

 most successful animals in, 367- 



368 

 role of salt spray in, 368 

 from sea to land routes of, 367-368 

 sea organisms in salt marshes 



and, 368 

 wind action in, 368 

 geologic: 

 dominance of amphibians in, 24 

 dominance of giant reptiles in, 24 

 dominance of mammals in, 24-25, 



25-26 

 dominance of marine life in, 24 



Index 443 



