Abstract
MR. CHAS. DIXON has discovered a new law of geographical dispersal of species, and he expounds its capabilities in the Fortnightly. Here is a statement of his conclusions:—“ Species in the northern hemisphere never increase their range in a southern direction; they may do so north, northeast, or north-west, east or west. Species in the southern hemisphere never increase their range in a northern direction; they may do so south, south-east, or south-west, east or west. The tendency of life is to spread in the direction of the poles. Among the six corollaries which I have drawn from this law, mention may be made of the following. By the fourth corollary, species never retreat from adverse conditions. If overtaken by such they perish, or such portion of the species that may be exposed to them. By the fifth corollary, extension of range is only undertaken to increase breeding area. By the sixth corollary, contraction of range is only produced by extermination among.sedentary species, and probably also by extermination (through inability to rear offspring) among migratory species that are neither inter-polar nor inter-hemisphere.… If this law of geographical distribution be true, polar dispersal of species—in other words, from the direction of the poles towards the equator—is a myth.” Mr. Dixon brings forward a number of facts in support of his theory, which will no doubt be given the consideration it deserves.
Article PDF
Rights and permissions
About this article
Cite this article
Science in the Magazines. Nature 51, 545 (1895). https://doi.org/10.1038/051545a0
Issue Date:
DOI: https://doi.org/10.1038/051545a0