CREATION BY EVOLUTION
mislead. It was based on the belief that species are fixed and immutable, and its use encourages that belief. That “species are species” is a statement often made in support of the idea that naturalists in practice treat species as fixed.
The circulus, on the other hand, is a natural grouping, which adopts evolution as a fact and as achieved by slow variation in all the members of a group in various directions. Each circulus has what Bateson called a centre of organic stability, and most of its members tend to be near the centre so long as the condition remains the same. Wherever during the growth of the Cutch Montlivaltia the sediment deposited on the sea floor accumulated steadily, most of the corals would have the same ratio of diameter to height; but if it accumulated at one place more quickly than at others, the centre of organic stability at that place would be with corals that were higher in proportion to their width.
The circulus provides a nomenclature which is consistent with the view that evolution results from changes affecting the mass of individuals belonging to a group and which relieves the naturalist of worrying over, say, the number of species among British brambles. Discussions of such problems, except in so far as they stimulate close observation, are comparable in utility with the mediaeval arguments as to how many angels could stand on the point of a needle.
REFERENCES
- Bateson, W. The Study of Variation, Treated With Special Regard to Discontinuity in the Origin of Species. 1894.
- Bolton, H. Insects from the Coal Measures of Commentry. 56 pp., 3 pl. 1925.
- Gregory, J. W. Catalogue of Fossil Bryozoa in the Department of Geology, British Museum. The Jurassic Bryozoa, pp. 1, 22–28. 1896. Jurassic Fauna of Cutch, Vol. II, pt. 2. The Corals, pp. 17–23. 1900. Palaeontologia Indica, ser. IX.
[ 122 ]
