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Dispersal during the Glacial Period.
The identity of many plants and animals, on mountain-summits, separated from each other by hundre...
Means of Dispersal.
Sir C. Lyell and other authors have ably treated this subject. I can give here only the briefest ...
Present Distribution Cannot Be Accounted for by Differences in Physical Conditions
In considering the distribution of organic beings over the face of the globe, the first great fac...
Summary of the preceding and present Chapters.
I have attempted to show that the geological record is extremely imperfect; that only a small por...
On the Succession of the same Types within the same Areas, during the later Tertiary periods.
Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely al...
On the State of Development of Ancient compared with Living Forms.
We have seen in the fourth chapter that the degree of differentiation and specialisation of the p...
On the Affinities of Extinct Species to each other, and to Living Forms.
Let us now look to the mutual affinities of extinct and living species. All fall into a few grand...
On the Farms of Life changing almost simultaneously throughout the World.
Scarcely any palæontological discovery is more striking than the fact that the forms of life chan...
On Extinction.
We have as yet only spoken incidentally of the disappearance of species and of groups of species....
On the Slow and Successive Appearance of New Species
Let us now see whether the several facts and laws relating to the geological succession of organi...
On the sudden Appearance of Groups of allied Species in the lowest known Fossiliferous Strata.
There is another and allied difficulty, which is much more serious. I allude to the manner in whi...
On the sudden Appearance of whole Groups of allied Species.
The abrupt manner in which whole groups of species suddenly appear in certain formations, has bee...
On the Absence of Numerous Intermediate Varieties in any Single Formation.
From these several considerations it cannot be doubted that the geological record, viewed as a wh...
On the Poorness of our Palæontological Collections.
Now let us turn to our richest museums, and what a paltry display we behold! That our collections...
On the Lapse of Time, as inferred from the rate of Deposition and extent of Denudatym.
Independently of our not finding fossil remains of such infinitely numerous connecting links, it ...
On the Absence of Intermediate Varieties at the Present Day.
In the sixth chapter I enumerated the chief objections which might be justly urged against the vi...
Summary of Chapter.
First crosses between forms, sufficiently distinct to be ranked as species, and their hybrids, ar...
Hybrids and Mongrels compared, independently of their fertility.
Independently of the question of fertility, the offspring of species and of varieties when crosse...
Fertility of Varieties when Crossed, and of their Mongrel Offspring, not universal.
It may be urged as an overwhelming argument that there must be some essential distinction between...
Reciprocal Dimorphism and Trimorphism.
This subject may be here briefly discussed, and will be found to throw some light on hybridism. S...