mach into the duodenum, or upper portion of the bowels, where it is farther mixed with two fluids one of a highly acrid nature, named bile, the other bland, and resembling very nearly the saliva which is secreted in the mouth. The bile precipitates the feculent parts of the chyme. The use of the pancreatic juice has never yet been satisfactorily explained. Besides these fluids, the mass is farther mixed by another poured out from numerous small glands, situated in the inner coats of the intestines.

By a wonderful law of the Great Creator, the feculent parts precipitated from the general mass, occupy the centre of the bowel; while the milky portion, destined for the nourishment of the system, adheres closely to the walls of the intestine, from whence it is sucked up by innumerable vessels, named lacteals, situated there for that purpose. These vessels all unite in conveying the chyle, as it is now termed, to small bodies called glands, into which they lose themselves; but from which other, though less numerous vessels, emerge, and convey their contents into a reservoir, called the receptacle of the chyle, from whence it is conveyed by another vessel named the thoracic duct, into the left subclavian vein, where it terminates near the heart; into which, however, it is not thrown in a continued stream, but, as it were, drop by drop. This gradual introduction is managed by a particular contrivance in the construction of the vessel.

Analogous to the lacteals, or vessels by which the nutritious particles of our food are carried into the cir culation, are the lymphatics-a set of vessels of exactly the same construction, whose office is to take up fluids from the surface of any cavity of the body, and carry them into the blood, from whence they may be ejected, if necessary, by the ordinary ontlets.

Having traced the chyle into the circulating system, I now return to trace the remaining contents of the intestines.

We have already seen, that chyle is formed in the first portion of the gut, perhaps in its most perfect form; consequently, the lacteals, or vessels which carry it away, are found to be more numerous here than in any other part of the bowels. These vessels are still found, however, throughout the whole extent of the small intestines; but few, if any, have been observed beyond their termination.

The contents of the bowels, when they pass from the small into the large intestines, are found to undergo a decided change, from a bland and inodorous substance becoming fœtid and more consistent, and passing on to their lower extremity more slowly. The lower portion of the bowels, called rectum, (or straight gut), is a large pouch, forming a receptacle for their feculent contents. When the rectum becomes distended, uneasy sensations are felt, which continue to increase until its contents are evacuated.

SECTION II.-Circulation of the Blood.

HAVING briefly mentioned the changes which the aliment undergoes in the process of digestion, and traced that part of it destined for the support of the body, into the blood, and the remaining feculent matter out of the body, it may now be proper to follow the former a little farther, and shortly to notice some of the changes which that most important fluid undergoes in its circulation through the system.

The blood is sent from the heart through every part of the body, in tubes called arteries; one of these passes upwards, named the ascending, and another downwards, named the descending arteries; the first supplying all that part of the body which is above the heart,-the second, all that part which is below it. These vessels give off branches in their several courses, which are farther divided, and finally terminate either in ramifications over every part of the body, or in minute vessels, which collect the blood, and carry it back again to the heart.

As the blood passes downwards, it gives off much of its watery particles by the kidneys, but it is constantly deteriorated as it proceeds. For freeing it from these deteriorations, nature has not, as in the case with the food which is taken into the stomach, provided one, but many thousand outlets, which terminate in the skin.

These give off this useless matter in the form of perspiration from the surface of the body, in phlegm from the nostrils, and in many other ways. What remains of the blood thus purified, is by the veins conveyed back to the heart, near to which, as we have seen, it' receives new and constant supplies from the chyle, thrown into it from the thoracic duct. The blood passes on to the heart: the right auricle receives the trunks of two large veins, one at the upper, the other at the lower part. At their union the vessels are dilated, forming what is called the venous sinus. The blood brought there, by the contraction of the auricle passes into the right ventricle, and from thence into the pulmonary artery, by which it is circulated through the lungs by its vast multiplicity of branches.

In the lungs, the blood is farther purified by giving off a substance named carbonic acid gas, which is ejected in the ordinary exhalations. While the air we breathe removes from the blood this deleterious aerial fluid, it imparts to it another called oxygen gas, by which it is changed from a dark grumous colour, to one of a bright scarlet hue, and thus again fitted for nourishing the multifarious tissues of which the body is composed. It is this addition of oxygen to the blood which preserves the uniform heat of our bodies.

When the blood has undergone these important changes in the lungs, it is conveyed again through the pulmonary veins into the left auricle of the heart, which

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propels it into the left ventricle, whence it is sent into the aorta to be dispersed all over the body, as has been already shewn.

SECTION III.-The Nervous System.

Having hastily glanced at the different stages of digestion, the manner by which the blood is supplied from this source; and described the course and manner of its circulation through the system, it will now be proper briefly to advert to another set of vessels, which are not less necessary to the healthy discharge of the several functions of the body than those we have been considering, although the manner in which they perform their functions has not hitherto been very satisfactorily explained. These constitute the nervous system, and have their origin in the brain.

The brain, as every one knows, is situated in the head, where it is protected from accidents by the skull, a compact bony covering, arched all over it. Like every other structure of the body, the brain derives its nourishment from the blood. It is generally regarded as the more immediate organ of the immaterial principle conferred upon man by his Almighty Creator, as a reflection of his own image, it is besides of the utmost importance in the animal economy. But as organization and mind are so