 | Bradley A. Thayer - 2009 - 452 lehte
...independently of Charles Darwin, succinctly captured a major part of the answer, natural selection: "There is a general principle in nature which will...variations, departing further and further from the original type."1 However, a complete answer to the question requires a discussion of Darwin's thought, particularly... | |
 | Joseph E. Harmon, Alan G. Gross - 2007 - 353 lehte
...naturalists, and has led to a very general and somewhat prejudiced belief in the stability of species. . . . But it is the object of the present paper to show...tendency of varieties to return to the parent form. The life of wild animals is a struggle for existence. The full exertion of all their faculties and... | |
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... even identical with those of domestic animals, and are governed by the same laws as regards their permanence or further variation. But it is the object of the present paper to show that this assumption is altogether false, that there is a general... 
