Among the Spartans all newly born children were subject to a careful examination or selection. All those that were weak, sickly, or affected with any bodily infirmity, were killed. Only the perfectly healthy and strong children were allowed to live, and they alone afterwards propagated the race.

An irrefutable proof that such single-celled primaeval animals really existed as the direct ancestors of Man, is furnished according to the fundamental law of biogeny by the fact that the human egg is nothing more than a simple cell.

Man is not distinguished from [the animals] by a special kind of soul, or by any peculiar and exclusive psychic function, but only by a higher degree of psychic activity, a superior stage of development.

Nothing is constant but change! All existence is a perpetual flux of "being and becoming!" That is the broad lesson of the evolution of the world.

By ecology we understand the total science of the connections of the organism to the surrounding external world.

There is no doubt that the course and character of the feared 'European war'... will become the first world war in the full sense of the word.

The succession of individuals, connected by reproduction and belonging to a species, makes it possible for the specific form itself to last for ages. In the end, however, the species is temporary; it has no "eternal life." After existing for a certain period, it either dies or is converted by modification into other forms.