| |strongly Effects of | | | |advocated. changes of | |Struggle for existence; | | food. | |stronger devour the | |Natural |Domesti- |weaker. Competition | |selection. Effects of |cation |stated in case of ai or |Species are | domesti- |briefly |sloth. Balance of |"different |Sexual cation. |referred to. |nature. |modifi- |selection. | | |cations of | Effects of |Effects of |Effects of use and |one and the |Effects of use. (The |use: |disuse, discussed at |same type." |use and only examples|characters |length. | |disuse (in given are the|produced by | | |some callosities |their own |Vestigial structures the| |cases). on legs of |exertions in |remains of organs | | camel, of |consequence |actively used by | | baboon, and |of their |ancestors of present | | the |desires, |forms. | | thickening by|aversions, | | | use of soles |lust, hunger,|New wants or necessities| | on man's |and security.|induced by changes of | | feet.) | |climate, habitat, etc., | | |Sexual |result in production of | | |selection, |new propensities, new | | |law of |habits, and functions. | | |battle. | | | | |Change of habits | | |Protective |originate organs; change| | |mimicry. |of functions create new | | | |organs; formation of new| | |Origin of |habits precede the | | |organs before|origin of new or | | |development |modification of organs | | |of their |already formed. | | |functions. | | | | |Geographical isolation | |Isolation |Inheritance |suggested as a factor in| |"an |of acquired |case of man. | |important |characters | | |element." |(vaguely |Swamping effects of | | |stated). |crossing. | | | | | |