On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1909 - 430 páginas |
Dentro del libro
Resultados 6-10 de 35
Página 163
... continuous area , are generally so distributed that each has a wide range , with a com- paratively narrow neutral territory between them , in which they become rather suddenly rarer and rarer ; then , as varieties do not essentially ...
... continuous area , are generally so distributed that each has a wide range , with a com- paratively narrow neutral territory between them , in which they become rather suddenly rarer and rarer ; then , as varieties do not essentially ...
Página 165
... continuous must often have existed within the recent period in isolated portions , in which many forms , more especially amongst the classes which unite for each birth and wander much , may have separately been rendered sufficiently ...
... continuous must often have existed within the recent period in isolated portions , in which many forms , more especially amongst the classes which unite for each birth and wander much , may have separately been rendered sufficiently ...
Página 186
... continuous area , must often have been formed when the area was not con- tinuous , and when the conditions of life did not insensibly graduate away from one part to another . When two varieties are formed in two districts of a continuous ...
... continuous area , must often have been formed when the area was not con- tinuous , and when the conditions of life did not insensibly graduate away from one part to another . When two varieties are formed in two districts of a continuous ...
Página 245
... continuous area with graduated physical conditions . I endeavoured to show , that the life of each species depends in a more important manner on the presence of other already defined organic forms , than on climate ; and , therefore ...
... continuous area with graduated physical conditions . I endeavoured to show , that the life of each species depends in a more important manner on the presence of other already defined organic forms , than on climate ; and , therefore ...
Página 275
... continuous . I am aware that there are some apparent exceptions to this rule , but the exceptions are surprisingly ... continuously existed , in order to have generated either new and modified or the same old and unmodified forms ...
... continuous . I am aware that there are some apparent exceptions to this rule , but the exceptions are surprisingly ... continuously existed , in order to have generated either new and modified or the same old and unmodified forms ...
Otras ediciones - Ver todas
Términos y frases comunes
accumulated adapted affinities allied species America analogous ancient animals appear archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo endemic existing exterminated extinct extremely facts favourable fertilised fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate larvæ laws less living males mammals manner migration modification modified descendants natural selection naturalists nearly nest occasionally offspring organic organisation origin of species perfect pigeons plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary seeds sexual sexual selection Silurian slight sometimes South America sterility structure struggle successive supposed swimbladder tend theory variability variations varieties vary whole widely