Natality 



The production of offspring by organisms. 



Natatorial 



Refers to the swimming capacity of an organism. 



Natural Area 



An area of land in which organisms and geological proc- 

 esses are undisturbed by man, with as few controls as pos- 

 sible, cf. Primitive area. 



Natural Selection 



The agent of evolutionary change by which the organisms 

 possessing certain characteristics in a given environment give 

 rise to more offspring than those lacking such characteristics. 

 cf. Drift, genetic; Mutation. 



Nature Reserve 



See Natural area. 



Nature Sanctuary 



See Natural area. 



Neap Tides 



The lowest tides during a month, occurring about the 

 time of the moon's first and last quarters. 



Nearctic 



One of the faunal regions of the earth, in the realm 

 Megagea, includes North America except the tropical part 

 of Mexico. 



Necrosis 



The death of an organism or one of its parts. 



Nectar 



The sweet liquid secreted by special glands in flowers or 

 in other parts of plants, attractive to insects, cf. Nectary. 



Nectariferous 



Refers to a flower or plant that produces nectar. 



234 



