Church. — The Principles of Phyllotaxis. 243 
factory, it adds considerably to the completeness of the principles of proto- 
plasmic segmentation, and may be extended in several directions with 
further interesting results. It is only necessary to point out that the case 
of centric-growth is after all only a first step ; and the most elaborate 
growth forms of the plant-kingdom, as exhibited for instance in the seg- 
mentation of the leaf-lamina, may be approached along similar lines, and 
by means of geometrical constructions which are consequent on the more or 
less perfect substitution of eccentric and ultimately wholly unilateral growth- 
extension, which again must ever be of a retarded type. The subject thus 
rapidly gains in complexity ; but that the study of growth-form, which 
after all is the basis of all morphology, must be primarily founded on such 
simple conceptions as that of the ‘ growth-centre * which has here been put 
forward, should I think receive general assent, and in the case of the quasi- 
circle, there can be little doubt as to the extreme beauty of the results 
of the mathematical consideration. 
