While the idea of biology is now usually taken in this broad sense in most scientific works and made to embrace the whole of living nature, we often find (especially in Germany) a narrower application of the term. Many authors (mostly physiologists) understand by it a section of physiology--namely, the science of the relations of living organisms to the external world, their habitat, customs, enemies, parasites, etc. I proposed long ago to call this special part of biology œcology (the science of home-relations), or bionomy. Twenty years later others suggested the name of ethology. To call this special study any longer biology in the narrower sense is very undesirable, because it is the only name we have for the totality of the organic sciences. Like every other science, biology has a general and a special part. General biology contains general information about living nature; this is the subject of the present study of the wonders of life. We might also describe it as biological philosophy, since the aim of true philosophy must be the comprehensive survey and rational interpretation of all the general results of scientific research. The innumerable discoveries of detailed facts which observation and experiment give us, and which are combined into a general view of life in philosophy, form the subject of empirical science. As the latter, on the side of the organic world, or as empirical biology, forms the first object of the science of life, and seeks to effect in the system of nature a logical arrangement and summary grouping of the countless special forms of life, this special biology is often wrongly called the science of classification.