Here we must leave the remaining mass, which takes its course downwards into the larger bowels called the сӕсит, the colon, and the rectum. You must keep in mind that the soluble or fluid part of this alimentary mass is usually absorbed by veins into the blood; whilst the insoluble matter, chiefly, is passed onwards and downwards. This absorption is not, however, to the extent that some writers would have us to suppose. I would just remind you that the liquid part of the fæces, or excrementitious matter, is chiefly secreted from the blood on the internal surface of the large intestine called the colon, where the fæces proper are first formed.

To return to the lacteals or lacteal absorbents. The chyle is the nutritious part of the alimentary mass, the essence of aliment. It is conveyed from the small intestines by these lacteals to a kind of oval-shaped bag, the reservoir of the chyle, and therefore called, in technical language, the receptaculum chyli, the receptacle of the chyle. It rests on the front of the spine of the loins, and receives or is formed by the termination of the large trunks of these lacteals and the trunk of the lymphatic absorbents of the lower extremities. In this reservoir or receptacle the chyle and the lymph carried by the lymphatics are mixed together. At its upper part it is formed into a large tube or duct, and then takes the name of thoracic duct, because its principal course is within the thorax or chest. It ultimately delivers its contents into the part of union between the left subclavian and the left jugular vein; and being mixed with the venous blood, it soon arrives at the right side of the heart; and then into the lungs, to be there exposed to the assimilating influence of the oxygen of the atmospheric air inhaled. You must turn to the engraving No. VIII., and you will see a correct representation of this statement.

You remember the anatomy of the heart and lungs, as described in the preparatory part of my other treatise. The heart, you know, is placed between the lobes of the left lung; and is a very strong muscular organ, composed of two distinct and separate halves, for separate purposes. The right half receives the dark-coloured venous blood from all parts of the body, and

with which is commingled the chyle of the thoracic duct, and it circulates this mixed and impure blood through the lungs, where it meets with the purifying oxygen. You remember that this oxygen of the atmospheric air combines with the carbon of the venous blood, and with a portion of its hydrogen, to form carbonic acid and water, which are immediately expired in the breath. That the black-red venous blood is changed by the exposure into bright vermilion red arterial blood, which is also surcharged with oxygen. In this state it is received by the left half of the heart, and by it is circulated through all parts of the body for nutrition, change of tissue, life, and organization.

I have not yet informed you of the composition of the blood. It is quite necessary, however, that you have some knowledge of it, because of its intimate relation with health, disease, and its treatment. The human blood consists of many component elements. Its proximate compounds are included in the following, namely, fibrine, albumen, salts, and red corpuscules or particles suspended in the watery fluid called, in technical language, liquor sanguinis, or the liquid of the blood. These different compound substances can be separated from the blood by analytic processes.

Some variety of opinion still exists on the supposed uses of these several compounds. I can safely state to you, however, that the fibrine is the chief substance for the purpose of nutrition of the body in the renewal of tissue. The salts of the blood are of different kinds, and in them are compounds of iron. It is an established doctrine that the salts of iron in the blood become the cause of its redness, and are also concerned in its electricity.

The internal structure of the heart is of excellent adaptation for the purposes designed, in its auricles and ventricles, and its different valves; also in the strong membranous bag which contains it, and which is called the pericardium. The lungs occupy the chest, and are in the form of lobes; there being three in the right side of the chest, and two in the left one, between which is placed the heart, occupying, as it were, the place of a lobe. The heart and lungs, you perceive, are properly de

nominated the secondary and finishing organs of digestion and blood-making.

On the next page I have appended a woodcut engraving of the essential organs, that you may have their correct relative position to each other before you.

You must keep in mind, dear Sir, that all these organs just stated perform the functions of organic life; and for this they have their system of organic nerves, with the organic nervous centres, called ganglions, or ganglia, a Greek word for knots, because they are in the course of these nerves like knots. And know, also, that the functions of animal life have a distinct system of nerves, of which the brain may be considered the one great ganglion. These particulars I have alluded to before; nevertheless, I repeat the allusion to their existence, to impress your non-medical mind more strongly concerning them; because they are of such momentous bearing, and ought to be well known and remembered.

You must not forget that the organic nerves are always without feeling in their healthy state; and that the animal nerves only are the instruments of sensation. Surely you cannot but perceive the Divine wisdom and goodness displayed in this arrangement. You see that all the vital functions are in this way carried on without our consciousness or feeling, and equally without our will or part in the matter. Were it otherwise, we should become our own destroyers in many ways. But what things are indispensable for our health, and comfort, and very existence, are placed beyond our observation and control. How supremely wise and beneficent is this arrangement!

I have now given you a brief account of the digestive function; also of the lungs and heart, the organs of respiration and circulation of the blood, which latter are the finishing processes for the one purpose which they all serve, namely, the nutrition of the body. I will now briefly treat of the function of nutrition in its association with other important functions. I mean the generation of heat, and the formation of the animal substance called fat, in connection with the renewal of tissue, and

a. The cut edges of the ribs, forming the lateral boundaries of the cavity of

the thorax.

b. The Diaphragm, forming the inferior boundary of the thorax, and the division between the thorax and the abdomen.

c. The cut edges of the abdominal muscles, turned aside, exposing the general cavity of the abdomen.

1. The cut edge of the pericardium

turned aside.

2. The heart.

3. The great vessels in immediate connection with the heart.

4. The trachea, or wind-pipe.

5. The lungs.

6. The liver.

7. The stomach.
8. The large intestines.
9. The small intestines.
10. The urinary bladder.

the action of the heart and lungs. This will make it necessary that I notice the different kinds of food, and the various purposes they serve in the animal economy.

I must remind you that many animal and vegetable substances consist of the same elementary ingredients in but slightly different proportions to each other. These ingredients are oxygen, hydrogen, nitrogen or azote, and carbon. Of the animal and vegetable substances, I mentioned starch, sugar, gum, and fat. I may add, that the bile, which the liver secretes from venous and carbonized blood, is so nearly allied to fat, in its component elements, that they are convertible into each other.

I have also already stated that nitrogen is the chief and distinguishing element of animal matter, whilst carbon is equally the fundamental element of vegetables. Again, you are to recollect that the tissues of the body are formed from the blood; and it therefore follows, that only those alimentary substances which are capable of conversion into blood can serve to build up the human frame in its three principal component tissues, namely, the muscular, the nervous, and the cellular.

Liebig has divided the food of man into two classes, which he terms nitrogenous and non-nitrogenous; azotized and non-azotized; meaning, of course, that one class contains nitrogen or azote, whilst the other does not. The former are capable of being converted into blood, the latter are incapable of such transformation. You now understand that out of the former are formed the three great tissues of the body just mentioned; and you must especially notice, that the other class of substances, in the normal state of health, serve to support the process of respiration. Liebig terms the former class the plastic elements of nutrition; and he terms the latter the elements of respiration. I must explain, to be plain, that the word plastic is of Greek origin, and signifies, in the verb, to form, that is, the elements out of which are formed the three tissues of the body, namely, the muscular, the nervous, and the cellular. Among these he reckons vegetable fibrine, vegetable albumen, vegetable caseine, animal flesh, and animal blood. Among the elements of respiration are fat, starch, gum, cane-sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer, and spirits or alcohol. There is another proximate principle called gelatine, which may be classed among the plastic elements; but it serves only to