Morphology

Morphology, the science of organic form. The name, originally due to Goethe (1817), has been understood in widely different senses, being used sometimes as synonymous with anatomy (q.v.), sometimes for organography, sometimes for histology (q.v.), and sometimes for a more purely abstract discussion of form. Haeckel, in his Generelle Morphologic (1866), divides the subject into tectology, the study of organic individuality, and pro morphology, the stereometry or crystallography of organisms. Promorphology is the attempt to reduce the complex-curved surfaces of organisms to definite mathematic expression. Two of the most remarkable instances of this are the laws of phyllotaxis (q.v.), and the law of the logarithmic spiral which governs the curvature of the shells of Gastropoda. The occurrence of comparatively precise geometric form among unicellular organisms has suggested that the excretion of silica to form the shells of diatoms or radiolarians may be determined by centres of vibration and rest in their protoplasm, similar to those in fine dust on a metal plate vibrated by a violin-bow.

Morphology may also well be taken to include the discussion of the causes of modification of form, such as mechanical pressure or irritation, hypertrophy, atrophy, cohesion or chorisis, though these border on the provinces of physiology and pathology. The parallelisms of development in related organisms (homology), and in those adapted for similar surroundings (analogy), may also well find a place in this study.