natural generalization
natural genetic transformation
natural genetic variation
natural gradient
natural grasslands
natural group
natural growth
natural habitats
natural hazards
natural health products
natural history

natural history collections
natural history study
natural host
natural host plant
natural hosts
natural hybridization
natural hydrological regime
natural immune response
natural increase
natural infection
natural infections
natural inhabitant

natural inhibitor
natural killer
natural killer/T-cell lymphoma
natural killer cell activity
natural killer cell cytotoxicity
natural killer cell function
natural killer cell receptors
natural killer cells
natural killer T cells
natural kinds
natural laboratory
natural lakes

natural landscapes
natural language
natural languages
natural law
natural levels
natural ligand
natural light
natural logarithm
natural materials
natural mating
natural mechanism
natural menopause

natural microbial communities
natural microflora
natural mixture
natural molecule