HYGIENIC pathology, or the plan of curing the disorders of the human organism by the aid of the remedial agencies of Nature, is founded on the fact that disease is not only a wholly abnormal condition, but that, within the years allotted to the individuals of our species, there is a strong healthward tendency in the constitution of the human system, which tendency does not fail to assert itself as soon as the predisposing cause of the disorder has been removed. In the treatment of consumption and scrofula, the principles of this theory have been generally recognized; but I believe that their application to the nervous diseases (asthenia, neurosis, chlorosis, hysteria, nervous debility) is destined to effect a still greater reform in the present system of therapeutics.
The study of biology is largely a study of hereditary influences. In the form and structure, in all the peculiar life-habits of each organic being, we can trace the outcome of ancestral transmissions, and, as a general rule, the persistence of such peculiarities corresponds to the length of time during which the influence of their causes was impressed upon the character of the species. The period of artificial civilization, even if considered as coeval with the era of recorded history, is but a moment compared with the ages during which man-like creatures, the ancestors of our domestic animals and the prototypes of our cultivated plants, existed in the warmer zones of our planet. After six thousand years of cultivation on parched hill-sides, the vine is still by preference a tree-shade plant. After many thousand generations of cats have been fed and petted in daytime and neglected after dark, puss is still a night-prowler. Barnyard fowl have still a predilection for thorny jungles, and in the plains of Russia the descendants of the mountain-goat climb wood-piles and cottage-roofs. In the constitution of all organic beings there is a tendency to revert to the original life-habits of the species. Biologists have long recognized the significance of that law, but its hygienic importance has hardly begun to be understood. For it implies not less than this: That the vital functions of every living being are performed more easily and more vigorously under the conditions to which the constitution of its organism was originally adapted. A swamp-boa may subsist for years in a dry board cage; eagles have been chained to a post for a quarter of a century, and lost the gloss of their feathers, their vigor, their courage, though not their lives. No drugs would cure the ailments of such captives; but restore them to their native haunts, and see how fast