(3) V/ater'-amounts available, depth, composition, chemical reactions, 



currents, light, temperature, snow, ice. 



(4) Atmosphere—pressure, movements, temperature, moisture, light, 



(5) Changes in physical surroundings — relation of age-lojig changes in 



topography and climate to the development, migration, establishment, 

 isolation, and extinction of the mammalian community* 



(6) Physical environment in relation to daily and seasonal activity — effects 



of weather, climate, and daily and seasonal cycles on the activity of 

 the mammal (fig. 4), on hibernation, estivation, or other periodic 

 phenomena, on nocturnal and diurnal activities, and on migration 

 (regular or irregular); climate and fluctuations in numbers; effects 

 of long days, very dark days, full moon, dark of the moon, and 

 similar phencanena on habits; hours of activity and rest on part of 

 different mammals; times of appearance and disappearance, as of bats. 



6. Plant surroundings. 



(1) Plants of the land — above and below the surface; plants of the water. 



(2) food and shelter relations between mammals and plants. 



(3) Mammals as disseminators of plants. 



(4) Mammals as checks on plant growth, as enemies of plants. 



(5) Plants causing irritation-; infection and transmission of bacterial 



diseases to mammals and man; periodicity of contagious diseases in 

 mammals; degree and rapidity of recovery; manner of recovery, 

 natural medicines, healing substances or activities. 



(6) Relation between development of plants and animals. 

 C. Animal surroundings. 



(1) The mammal and its animal associates—in air, soil, water, trees, or 



on land; in burrows, dens, shelters, nests, trails, about water holes, 

 salt licks, stamping grounds, or elsewhere* 



(2) Relation of the mammal and other animals— relation to others of same 

 kind, to friends, partner's, parasites, pr^y; eissociations with other 

 individuals or groups; herding or flocking; competition and adaptation 

 among animals; ssnnbiosis, commensalism, warfare, as illustrated 

 among mammals and their associates. 



(3) Animal-caused disease— effects; infection and transmission to other 



wild mammals, domestic animals, or man. 



13 



