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Principles of Physiology. General and Comparative. By
Wm. B. CARPENTER, M. D., F. R. S., F. G. S., &c., &c., &c. Third edition, with three hundred and twenty-one Wood Engravings. Philadelphia. pp. 1098.
There are few studies which present matter of deeper or more absorbing interest to the inquiring mind, than the study of Physiology. It is the study, as the name imports, of the laws of life: its domain is as broad as animated creation ; so that, wherever, from the most complex organism, enriched with the most precious gifts of infinite Beneficence, to the very simplest cell, destitute of every thing but its vitality, wherever there is life, there is the field of the physiologist.
Now this life of which we speak is the greatest of the mysteries in the midst of which we exist : though the study of centuries, philosophers have but just begun to penetrate the outward boundary of this immense field, the ever-receding limits of which must provoke to ever-renewed research. With what profound interest does that study commend itself to us, which announces as its peculiar field the investigation of the laws of being; which professes to unravel, or at least attempts the task of showing, the mode of growth, of increase ; which proposes to tell us how it is that the acorn becomes the oak ; how, in short, immaturity by an unerring law passes on to maturity; maturity, to decay; decay, to death.
There are concerning these topics a multitude of questions pressing on VOL. XI.
the curious mind for solution ; to this end it interrogates all nature, puts science to the rack, and draws out the hidden things of creation. It disentombs the past, and dissects the present; the alembic, the retort, the scalpel, and the microscope are brought into activity well nigh unceasing, that they may make their depositions, and give up their evidence.
The cause of life has as yet only declared itself by its effects; some of the laws of being have indeed been discovered, though these so-called laws are for the most part but the expression of the conditions of being, rather than the reasons for it; they show us how it may be, not why.
The study of our own bodies shows to us a mechanism which regarded as purely physical is of the most remarkable contrivance ; simple in its operations and wonderful in its results; as we explore it more, it ever furnishes new matter for devout thankfulness, and never ceases to draw out our admiration, as new discoveries unfold to us new views of its structure and operations. But then it is not a mere physical machine ; these bodies are but the mortal vehicles of immortal
To these muscles and bones are chained the ethereal spirit, whose mandates borne along these nerves are expressed by these subject members.
But we need not look beyond the tiny plant we press beneath our feet, to find matter that shall amply challenge our admiration, and excite our wonder. So various, well nigh infinite in number, are the developments of life. They reach from the simplest vegetable structure up through all the minute gradations and modifications that distinguish kind and class, until by imperceptible degrees we pass from the vegetable to the animal kingdom, (the boundary between which is even yet in dispute,) and thence on from the very lowest manifestations of animal life up to its culminating point in man.
Simplicity reigns throughout the realm of nature; all unnecessary complexity is rejected, and means apparently the simplest accomplish the most amazing results. This simple plant, of a single cell, for knowledge of whose existence we are indebted to the microscope, when its laws and habits are known, is found to be the type of that mighty tree, which is but another plant, and not of it only, but of all organized structure. And not only does simplicity mark the handiwork of nature ; it carries another, that of universal harmony. Nature everywhere harmonizes with herself. All her works are gov. erned by universal laws; the greatest apparent anomalies are found on careful investigation to be amenable to laws, and no exception or violation thereof.