ABSTRACT

The first great law which follows directly and of necessity from natural selection is that of separation or differentiation, frequently also called division of labour, or separation of forms; Charles Darwin calls the general principle divergence of character. The different function naturally produces its reaction in changing the form, and the physiological division of labour necessarily determines the morphological differentiation, that is, the “divergence of character.” The variability or adaptability of species, under the influence of the struggle for life, necessitates the continual and progressive separation or differentiation of varieties, and the perpetual separation of new forms. The most distinguished palaeontologists have pointed out the law of progress as the most general result of their investigations of fossil organisms. Frequently a relapse to simpler conditions of life takes place, and by adaptation to them a divergence in a retrograde direction. If, for instance, organisms which have hitherto lived independently accustom themselves to a parasitical life, they thereby degenerate or retrograde.