In order really to understand the states of health and disease, an acquaintance with the nature of organization, and of the vital processes of which it is the seat and the instrument, is indispensable: it is for this reason that the exposition of structure and function, attempted in this first part of the work, is somewhat full; but there cannot be a question that, if it accomplish its object, it will not only enable the account of health and disease in the subsequent part of it to be much more brief, but that it will, at the same time, render that account more intelligible, exact, and practical.
S. S.
THE
PHILOSOPHY OF HEALTH.
CHAPTER I.
Characters by which living beings are distinguished from inorganic bodies—Characters by which animals are distinguished from plants—Actions common to plants and animals—Actions peculiar to animals—Actions included in the organic circle—Actions included in the animal circle—Organs and functions defined—Action of physical agents on organized structures—Processes of supply, and processes of waste—Reasons why the structure of the animal is more complex than that of the plant.
The distinction between a living being and an inorganic body, between a plant and a stone, is, that the plant carries on a number of processes which are not performed by the stone. The plant absorbs food, converts its food into its own proper substance, arranges this substance into bark, wood, vessels, leaves, and other organized structures; grows, arrives at maturity, and decays; generates and maintains a certain degree of heat; derives from a parent the primary structure and the first impulse upon which these varied actions depend; gives origin to a new being similar to itself, and, after a certain time, terminates its existence in death.
No such phenomena are exhibited by the stone; it neither absorbs food, nor arranges the matter of which it is composed into organized structure; nor grows, nor decays, nor generates heat, nor derives its existence from a parent, nor gives origin to a new being, nor dies. Nothing analogous to the processes by which these results are produced, is observable in any body that is destitute of life; all of them are carried on by every living creature. These processes are, therefore, denominated vital, and, being peculiar to the state of life, they afford characters by which the living being is distinguished from the inorganic body.