Lastly, isolation, by checking immigration and consequently competition, will give time for any new variety to be slowly improved; and this may sometimes be of importance in the production of new species. If, however, an isolated area be very small, either from being surrounded by barriers, or from having very peculiar physical conditions, the total number of the individuals supported on it will necessarily be very small; and fewness of individuals will greatly retard the production of new species through natural selection, by decreasing the chance of the appearance of favourable variations.

One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die.

There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has…

To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for …

The powerful retractile talons of the falcon- and the cat-tribes have not been produced or increased by the volition of those animals; but among the different …

That intermediate manifestation of the divine process which we call the DNA code has spent the last 2 billion years making this planet a Garden of Eden. An int…

One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die.