Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation.

We are compelled by reflection to recognize that God is not to be placed against the material world [as in Christianity], but must be placed as a 'divine power' or 'moving spirit' within the cosmos itself ... All the wonderful phenomena of nature around us, organic as well as inorganic, are only various products of one and the same original force.

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.

Civilization and the life of nations are governed by the same laws as prevail throughout nature and organic life.

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

The nucleus has to take care of the inheritance of the heritable characters, while the surrounding cytoplasm is concerned with accommodation or adaptation to the environment.

Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation.