WESEN UND BEDEUTUNG DER LIMNOLOGIE.

The modern limnology has arisen from hydrobiology and it was recognized at last as a part of the general ecology or the science of the "household of Nature". The above account is in all essentials a story told in the first person singular, in which the author accounts for his own ideas. In 1882 S. A. Forbes designated the lake as a "microcosmos", in 1901 F. A. Forel called it an "Organ der Erde", but not until 1914 were these two basic principles in limnology amplified. "Lebensgemeinschaft" plus "Lebensraum" is considered a higher biological unit, because of the interplay between them. This modern view out of hydrobiology - the science which treats the life in the water - makes limnology, the science of the life of the fresh waters. The first thing to be done was, on the basis of the biological conditions governing the production, to divide the fresh waters, more particularly the lakes, into types. The fresh waters are, however, not an "autarc" microcosmos in the strictest sense of the word, but form part of the surroundings of which they depend. All biotopes depend on each other and form part of the great "Lebens- raum" of the earth. Thus the lake becomes a part of a constantly higher entity of the "Lebensraum". Limnology, therefore, becomes one of the three branches of the more comprehensive science which treats the household of Nature, i. e. the general ecology. The three ecological divisions on the earth, the terrestrial, limnic and marine, are so intimately connected that what happens in one of them can only be understood if conditions in the two others are also considered. Nature is one great entity. By stressing the entity in the interrelationships the [ABSTRACT FROM AUTHOR]