The American Naturalist, Volume 43Essex Institute, 1909 - Biology |
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Page 54
... in this note may occur farther south than San Diego . WILLIAM A. HILTON . POMONA COLLEGE , CLAREMONT , CAL . NOTES AND LITERATURE EXPERIMENTAL EVOLUTION The Effect of the Environment 54 [ VOL . XLIII THE AMERICAN NATURALIST.
... in this note may occur farther south than San Diego . WILLIAM A. HILTON . POMONA COLLEGE , CLAREMONT , CAL . NOTES AND LITERATURE EXPERIMENTAL EVOLUTION The Effect of the Environment 54 [ VOL . XLIII THE AMERICAN NATURALIST.
Page 55
... effect of external factors upon organisms . It will doubtless surprise many that , although dealing almost ex- clusively with insects , the author reviews more than 1,200 papers . Even so , seasonal dimorphism , protective coloration ...
... effect of external factors upon organisms . It will doubtless surprise many that , although dealing almost ex- clusively with insects , the author reviews more than 1,200 papers . Even so , seasonal dimorphism , protective coloration ...
Page 56
... effect which is not easily reversed is given by Marchal ( 3 ) . Lecanium corni , a scale insect , becomes L ... effects of the environment . Powers has contributed a valuable paper ( 4 ) on the causes of variation in Amblystoma tigrinum ...
... effect which is not easily reversed is given by Marchal ( 3 ) . Lecanium corni , a scale insect , becomes L ... effects of the environment . Powers has contributed a valuable paper ( 4 ) on the causes of variation in Amblystoma tigrinum ...
Page 68
... effect a new group . It was not at first his idea that a single individual , or a small number of individuals , might occasionally develop evolutionary force enough to over - leap suddenly the imaginary bound- ary and become the nucleus ...
... effect a new group . It was not at first his idea that a single individual , or a small number of individuals , might occasionally develop evolutionary force enough to over - leap suddenly the imaginary bound- ary and become the nucleus ...
Page 70
... effects of man's selection among domesticated animals and plants , -without which , indeed , he admitted that he had no actual proof of the operation of natural selection , -it is difficult to realize the state of mind which led Mr ...
... effects of man's selection among domesticated animals and plants , -without which , indeed , he admitted that he had no actual proof of the operation of natural selection , -it is difficult to realize the state of mind which led Mr ...
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absence adaptation American animals appear bees breeding brown cells cent chromosomes corn plant correlation crinoids crossed curve Darwin dk.br dominant ecology eggs elementary species environment evidence evolution experimental experiments fact factors fertilization flowers fluctuating forms gametes genus green growth gynandromorphs hair color heredity heterozygote hybrids important index number individuals inheritance insects kelps L. H. BAILEY lamina large number larva larvæ Lessoniopsis lt.br male Mendelian Mendelian inheritance methods morphology muscular articulations mutation natural selection Notes and Literature observed offspring organs origin Origin of Species oyster pairs pangen paper Paramecium parent physiological pigment pinnule present problem produced Professor pure race RAYMOND PEARL rays Recapitulation Theory recent region relation Science seems selection index single sired specimens sporophytic stipe structure T. H. MORGAN theory tion unit characters variability variations varieties vegetation Vries yellow
Popular passages
Page 78 - But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position — namely, at the close of the Introduction — the following words : " I am convinced that natural selection has been the main but not the exclusive means of modification.
Page 156 - If numerous species, belonging to the same genera or families, have really started into life at once, the fact would be fatal to the theory of evolution through natural selection.
Page 69 - No man would ever try to make a fantail till he saw a pigeon with a tail developed in some slight degree in an unusual manner, or a pouter...
Page 135 - We are thus brought to the question which has been largely discussed by naturalists, namely, whether species have been created at one or more points of the earth's surface. Undoubtedly there are very many cases of extreme difficulty, in understanding how the same species could possibly have migrated from some one point to the several distant and isolated points, where now found. Nevertheless the simplicity of the view that each species was first produced within a single region captivates the...
Page 81 - Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part differs, more or less, from the same part in the parents.
Page 79 - One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal's or plant's own good, but to man's use or fancy.
Page 377 - ... 1 Papers from the Biological Laboratory of the Maine Agricultural Experiment Station. No.
Page 141 - The direct action of changed conditions leads to definite or indefinite results. In the latter case the organisation seems to become plastic, and we have much fluctuating variability. In the former case the nature of the organism is such that it yields readily, when subjected to certain conditions, and all, or nearly all the individuals become modified in the same way.
Page 138 - ... to natural selection, by affording a better chance of the occurrence of profitable variations. Unless such occur, natural selection can do nothing. Under the term of " variations," it must never be forgotten that mere individual differences are included.
Page 77 - There are, however, some who still think that species have suddenly given birth, through quite unexplained means, to new and totally different forms: but, as I have attempted to show, weighty evidence can be opposed to the admission of great and abrupt modifications. Under a scientific point of view, and as leading to further investigation, but little advantage is gained by believing that new forms are suddenly developed in an inexplicable manner from old and widely different forms, over the old...