Church . — The Principles of Phyllotaxis . 237 
however small, at which such a mathematical distribution of ‘growth- 
potential ’ may be considered as accurate ; and such a region is here 
termed a ‘ Growth- Centre l Since the interpretation of all complex phe- 
nomena must be first attacked from the standpoint of simple postulates, 
it now remains to consider the construction and properties of as simple 
a centre of growth as possible. 
Thus in the simplest terms the growth may be taken as uniform 
Fig. 40. Scheme for Uniform Growth Expansion : a circular meshwork of quasi- squares. 
Symmetrical construction from which asymmetrical homologues are obtained by the use of logarithmic 
spirals. 
and centric', the fact that all plant growth is subject to a retardation 
effect or may be frequently eccentric , may at present be placed wholly 
on one side, since the simplest cases evidently underlie these. The case 
of uniform centric growth is that of a uniformly expanding sphere ; or, 
