he says, "I esteem myself as composing a solemn hymn to the great architect of our bodily frame; in which I think there is more true piety, than in sacrificing hecatombs of oxen, or in burning the most costly perfumes; for I first endeavour, from his works, to know him myself, and afterwards, by the same means, to show him to others, to inform them how great is His wisdom, His goodness, His power." "The same conclusion, in fact, must be drawn from the examination of the structures of living beings, as from the consideration of the works of nature in general, that what we understand seems excellent in a degree far exceeding our ordinary conceptions, yet appearing more and more so, in proportion as it is minutely examined and attentively considered; and that we understand so much of the works of nature, as to warrant us in concluding, that we can only cease to admire when we fail to understand."

CHAPTER XIII.

DIGESTION.

THE fourth lecture begins by stating that the grand characteristic of living bodies is their power of applying surrounding substances to their own nurture and repair. He then introduces Mr. Knight's theory of vegetable nutrition; and proceeds to say that "In animals, the matters by which they are nourished, are, in general, taken into a receptacle or stomach, where it undergoes a process called digestion; and so analogous are the functions of life in vegetables and the lower kinds of animals, that Mr. Hunter considered this circumstance the chief criterion of distinction between the two classes." He gives that eminent Anatomist the credit of being the first person who broached and established the now generally received opinions respecting digestion. His observations and reflections suggested to him, that the liquors secreted by, or poured into the stomach, had the surprising power of dissolving the dissimilar food by which different animals are nourished, and converting it into a substance sui generis; this being the first and most important step to its ultimate conversion into that nutritive fluid, the blood, which is distributed to every part of their bodies. He was fully apprized of that variety of substances from which different animals derive their nourishment. He knew that the fibrous matter of vegetables, and the husks

of grain, are in general not susceptible of digestion by the gastric fluids; and yet that some insects live upon them. They first pour upon the woody substance a liquor which dissolves it, and in this state they swallow and digest it. "Thus also," adds Abernethy, "does that foe to literature, the book-worm, make his way through the most massy folios, solving the most difficult passages, and digesting all as he proceeds. Indeed he pours his sauce, or cooking liquors, with such profusion, as to tinge and affect the texture of the leaves to some distance round the circumference of the tunnel which he makes."

Although the gastric fluids have no sensibly distinguishing character-yet Hunter knew that they not only coagulated milk, but white of egg, and other nutritive fluids; thus first rendering them solid, that they might be detained in the stomach till they underwent the peculiar solution, called digestion. He knew that the gastric fluids checked and prevented the natural decomposition of animal and vegetable matter; that if putrid meat were swallowed by a hungry dog, it quickly lost all fetidness, and that no fermentation or putrefaction of food ever takes place in the stomach, under ordinary circumstances; whence it followed that digestion could not be the result of any common fermentative process. He must have known, also, that the peculiar fluid which digests food is not secreted at all times, but only when the stomach is excited by the stimulus of food, and not even then unless under favourable circumstances. If, after secretion has taken place, persons are suddenly killed by accidents, the gastric fluids will con

tinue for some time to act, not only upon the food, but also upon the now lifeless stomach itself, so as to form an aperture by which the contents escape.

Hunter's publication of his opinions on digestion, in the sixty-second volume of the Philosophical Transactions, printed in the year 1772, soon made them known throughout the scientific world, and led Spalanzani and others to make and publish experiments, which tended to confirm them. Many of these were cruel in the extreme; and little scrupulous as Hunter himself is admitted by Abernethy to have been in inflicting sufferings on animals, when the motive was apparently adequate, he nevertheless censured Spalanzani for the unmeaning repetition of similar experiments. It is with great pleasure that I quote Abernethy's own indignant and characteristic reprobation of such unjustifiable cruelty :-"I believe," he says, "Spalanzani to have been one of those who have tortured and destroyed animals in vain. I do not perceive that in the two principal subjects which he sought to elucidate, he has added any important fact to our stock of knowledge; besides, some of his experiments are of a nature that a good man would have blushed to think of, and a wise man would have been ashamed to publish; for they prove no fact requiring to be proved, and only show that the aforesaid Abbé was a filthy-minded fellow."

He then enters more fully upon the subject, and admitting the propriety of making experiments on living beings under fitting restrictions, he ends by expressing a hope, that the character of an English surgeon may never be

tarnished by the commission of inconsiderate or unnecessary cruelty, or by the publication of experiments disgusting to common decency.

We have in this lecture so complete a natural history of digestion, pursued through the whole series of animated existence, from man, namely, to the lowest creature that can be said, and scarcely said, to partake of the breath of life, that I should be doing great injustice were I to attempt to make any analysis of it consistently with the plan of this memoir. Suffice it to say, that Abernethy has done his friend ample justice in the illustration and confirmation of those views which, originating with Hunter, are entertained almost without any modification by physiologists at the present day. And not only will such as seek scientific information on the interesting subject of digestion be highly gratified by reading attentively the whole lecture; but all others likewise who take an interest in the wonderful operations of creative power, nowhere more manifest than in the infinitely diversified means subservient to the support of that life which can only have originated with a self-existent, Omnipotent, and Omni-present Being.