scopeofzoology

together broadly distinguish the different kinds of animals from each other. Early zoologists
dealt only with the description of shapes. It was not until the second and third decades of this
century that they turned to the description of sequences of movement, or the 'behavioural
structures' of animals. It can be argued that zoology has distinction as a subject only when
dealing with the building of three-dimensional shapes, and the assembly of patterns of
movement. That is to say, what is distinctly animal is found only in the evolution of
communities of cells to form organ systems and the establishment of behavioural structures
by which animals interact with each other and with their environment. The motivation of
zoologists is summarised by the questions "What is the use in having a particular shape and
mode of behaviour? Does it contribute to the animal's success? If so, How?" and "What
makes it happen?"
Questions on the origins of shape and size are still central to modern zoology. The most
original approach to escape the anatomist's method of comparing shapes piecemeal was to
view all changes in relative dimensions simply as the topical expressions of some
comprehensive and pervasive change of shape through development taking place mainly in
one direction. At the turn of the century, D'Arcy Thompson developed this approach to grasp
evolutionary transformations as a whole, viewing the change of shape as analogous to that
produced by distorting a sheet of rubber on which has been drawn a house or a face. Every
single aspect of the drawing changes but the transformation as a whole might be defined by
some quite simple formula describing the way the rubber had been stretched. Thompson's
methods were later developed by J.S. Huxley into more usable quantitative relationships
between the rate of reproduction of one part of the organism to another. This quantification of
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