into a coarse powder, and called granulated cocoa; or it is cut into slips, and called flaked cocoa. The husks are more or less removed in these preparations. Again the seeds are submitted to heat, the husks removed and the kernel somewhat broken: they are sold under the name of cocoa-nibs. Lastly, the husks are removed, the nuts are reduced to a paste, and various flavouring agents are added, as vanilla, and the cakes thus prepared are called chocolate.

The composition of one pound of these seeds in the form of cocoa-paste, is as follows:

If we compare this composition for one moment with tea and coffee, we shall see that the flesh-forming and heat-giving elements of food are greatly in the ascendant. The albumen and gluten are in larger proportions than in bread, or oats, or barley. There is no doubt, then, that when these seeds are eaten entire, or in the form of paste, that they constitute a highly nutritive article of diet.

Again, let us look at the fat. the paste consisting of pure fat,

Here we have half

and acting on the

system as any other kind of fatty matter: so that, in estimating the value of cocoa as an article of diet, we

must not estimate its medicinal action alone, but the influence of its heat-giving and flesh-forming matters.

The alkaloid it contains, and which is called theobromine, is, nevertheless, an interesting substance. It differs from theine in containing a larger quantity of nitrogen. It is, however, a curious fact, that recently theobromine has been converted artificially into theine; it is, therefore, not at all improbable that theobromine may be converted in the human body into theine, and act in the same way upon the nervous system.

Cocoa is prepared in various ways. The paste or powder is boiled with water, and sugar and milk are added according to taste. In this way, however, it can hardly be regarded as a substitute for tea and coffee; it is, in fact, a substitute for all other kinds of food, and when taken with some form of bread, little or nothing else need be added at a meal. The same may be said of chocolate, which only differs from cocoa in the more careful manner in which it is prepared, and the flavouring substances which are added to it. Chocolate may be mixed with water and milk, and taken in the same manner as cocoa. When a sufficient quantity of sugar is added, it is made into a variety of articles of confectionary, in the preparation of which our French neighbours so greatly excel us.

One of the delusions practised on the public is to call certain preparations of cocoa "homœopathic ; but analysis shows that these preparations, neither in their quality nor the proportions in which they may be taken, differ at all from ordinary cocoa.

The cocoa seeds roasted, and sold under the name of

"nibs," may be infused in boiling water in the same way as tea-leaves; and under these circumstances a beverage is obtained which in many respects resembles tea and coffee, as the albumen and fat are not taken up in this way.

The husks of the cocoa seeds which are separated in some of these preparations are not lost. They are said to contain a noticeable quantity of theobromine, and also the flavouring aromatic oil of the cocoa. They are sold for making a beverage which is not unlike tea or coffee in its action on the system.

I must now conclude my notice of this group of substances, which have gradually come to be used in such enormous quantities by mankind in the form of warm beverages. Whatever may have been the influence of a heated liquid in leading to their first use, I think you cannot but see that the principle they contain which addresses itself to the nervous system is the agent which has determined their special selection. It would, therefore, be unwise in the highest degree to neglect the study of these important agents. From what we already know, they are evidently potent for good and for evil, and it is only by a careful study of their action on the human body that we can expect to secure the one or prevent the other.

ON TOBACCO.

In this lecture I propose to make some remarks on those substances indulged in by man, known by the name of narcotics, and more particularly on tobacco. In approaching this subject, I am reminded of the connection that exists between food and medicine, and medicine and poisons. The more one investigates the relation of food to the human system, the greater must be the conviction that food is not only capable of maintaining healthy life, but, by proper modification, can be made the means of curing disease. Our life is so essentially dependent on food, that we may increase its activity by increase of food, and decrease it by decrease of food, and change its character by change of food. Diseases manifest themselves in an increase, or decrease, or a change of vital action. It

must be evident, therefore, that in the management of food we have the great means for the cure and removal of disease.

In the classification of food which I gave you at the commencement of these lectures, I showed you that certain substances which we habitually take as food act in the same way as medicines; hence I called them medicinal foods. Such substances are alcohol, the volatile oils, and the theinal principles. These are themselves powerful medicinal agents, or belong to groups of substances which yield them. From a medicine to a poison there is but a step, and that is not one of kind, but of degree. The alcohol that invigorates the stomach and cheers the social meal, recalls to life the frame exhausted with febrile poison, but kills when taken to excess. The oxalic acid of our spring tart is a pleasant febrifuge in fever, but poisoncus when swallowed by the ounce. Common salt is one of the great necessaries of life, but in drachm doses acts as an emetic, and may be accumulated in the system till it destroys life. Such, then, is the connection between food, medicine, and poison, that all our food may be made medicinal and all our medicines may become poisons.

If

I need not remind you how such a view as this lays the axe at the root of all pretensions to cure disease by remedies that can exert no influence on the system. you are eating and drinking, and men tell you they are curing your diseases with infinitesimal doses, don't believe them. Your food is exercising a far more powerful effect on your system than their remedies. The only remedies that can be rationally employed as medicines