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Export to Excel select * from OriginOfSpecies where ordinal = '70' order by subject, title, ordinal limit 4 (Page 1: Row)
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title
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description
01 - Variations Under Domestication 01-07 - Origin of Domestic Varieties from one or more Species 70 It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species; but by crossing we can only get forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bulldog, &c., in the wild state.

greyhound
greyhound

bloodhound
bloodhound


Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. Many cases are on record, showing that a race may be modified by occasional crosses, if aided by the careful selection of the individuals which present the desired character; but to obtain a race intermediate between two quite distinct races, would be very difficult. Sir J. Sebright expressly experimented with this object and failed.

The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) quite uniform in character, and everything seems simple enough; but when these mongrels are crossed one with another for several generations, hardly two of them are alike and then the difficulty of the task becomes manifest.

pigeon
pigeon
01 - Variations Under Domestication 01-08 - Breeds of the Domestic Pigeons, their Differences and Origin 70 From these several reasons, namely,- the improbability of man having formerly made seven or eight supposed species of pigeons to breed freely under domestication;- these supposed species being quite unknown in a wild state, and their not having become anywhere feral;- these species presenting certain very abnormal characters, as compared with all other Columbidae, though so like the rock-pigeon in most respects;- the occasional reappearance of the blue colour and various black marks in all the breeds, both when kept pure and when crossed;- and lastly, the mongrel offspring being perfectly fertile;- from these several reasons taken together, we may safely conclude that all our domestic breeds are descended from the rock-pigeon or Columba livia with its geographical sub-species.

Rock Pigeon
Rock Pigeon
02 - Variations Under Nature 02-03 - Doubtful Species 70 Certainly no clear line of demarcation has as yet been drawn between species and sub-species- that is, the forms which in the opinion of some naturalists come very near to, but do not quite arrive at, the rank of species: or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences. These differences blend into each other by an insensible series; and a series
impresses the mind with the idea of an actual passage.
04 - Natural Selection 04-07 - Illustrations of the Action of Natural Selection: 70 I will give only one, as likewise illustrating one step in the separation of the sexes of plants.