one for every two hundred and twenty red globules, the venous blood which flows out contains one to sixty (His) and even one to five or four. (Vierordt, Funke.) The influence which the spleen exercises in relation to the red globules is still so far from being decided, that some maintain that it is a seat of destruction of these elements (Béclard, Kölliker), while, according to others, it is a laboratory for their production (Funke, J. Bennett).

The following facts are adduced as proofs of its destructive function of the red globules: an animal in which ablation of the spleen has been accomplished, exists longer without food than one which is sound: its blood does not change as quickly into red globules; the lymph which comes from the spleen (for this organ also contains lymphatic vessels) is generally tinged with red. Some observers have remarked a sort of plethora (or hyperglobulia) in animals whose spleen has been removed; but these observations do not agree with the results furnished by clinical surgery.

The red globules are evidently destroyed in the spleen, as in any organ or tissue in which active transformation takes place; this may be readily observed in pathological cases, in which we find a large quantity of remains of the coloring matter of the red globules (paludal cachexia): but it is still more likely that a large number of red globules are formed in the spleen, in the physiological condition, in the sense that the white globules which were produced in it, are beginning to change into colored blood corpuscles: indeed, an abundance of globules, in an intermediate state between the white and the red, are found in the splenic veins, as also red globules, possessing all the features which distinguish young elements (small size, less flattened shape, greater resistance to the action of water, etc.).

There are also some glandular organs, resembling, no doubt, nearly the class of lymphatic ganglions and spleen; such as the thyroid gland, the thymus, and, perhaps, the supra-renal capsules; but our anatomical ideas on these subjects are not yet sufficiently precise, and our physiological theories are too hypothetical, to allow us to attempt profitably the study of these so-called vascular blood glands.

PART SIXTH.

DIGESTIVE SYSTEM.

I. OBJECT OF DIGESTION. - INANITION. - FOOD.

THE aim of the digestive functions is to transform the substances borrowed from without, so as to enable them to pass into the system, to be absorbed and carried into the current of the circulation, in order to renew the organs, and keep up their functions.

These reconstructive substances are food.

By privation of food, animals are reduced to a state of inanition: the inevitable consequences of prolonged inanition are gradual loss of weight, cold, and death; animals die when they have lost of their original weight (Chossat.)1

This loss of weight is produced sooner in some animals than in others: cold-blooded animals will endure privation of food thirty times longer than the warm-blooded, and sometimes, even, for an almost incredible space of time: thus Cl. Bernard has known frogs go entirely without food for nearly three years, while a small bird dies of hunger after two or three days.

Inanition, as observed in persons subjected to a strict diet, not only affects the general temperature, but also the daily variations in temperature: even when there is no fever, this may vary 3°. This fact should be taken into account, in estimating the temperature of persons suffering from intermittent fever, who have long been on a low diet.

Some of the alimentary substances, intended to repair the incessant waste of the system, are immediately absorbed; while others, which are deposited on the surface of the

Chossat, "Recherches Expérimentales sur l'Inanition." Paris, 1843, in 4to.

digestive organs, must first undergo a change, from being subjected to the influence of the juices of these organs. This is because the food, received into the mouth, traverses the different parts of the digestive canal successively, and is subjected in its course to various mechanical influences, especially that of the different fluids which serve to liquefy and transform it. These modifications are not generally very striking; they appear to affect only the state of cohesion of the substances; insoluble elements being rendered soluble, and coagulable elements incoagulable, etc., while the unchanged parts are thrown off.

No aliment is complete, unless it contains all the elements of which the tissues of the body are composed.

1. Beside their organic principles the animal and vegetable matters which we consume contain various mineral products: such are the alkaline or alkaline-earthy salts, sulphur, phosphorus, iron, all elements necessary to every cell of our organs. Iron is administered to a chlorotic person as food, because iron, which is one of the indispensable elements of the economy, has been diminished in the blood. These mineral substances alone, are incapable of supporting life; and if those which are borrowed from the organic kingdom are found sufficient for this purpose, it is only because they contain in themselves a certain proportion of mineral matters.

The mineral salt that appears most indispensable to nourishment is chloride of sodium. Daily experience proved long ago that man cannot do without this salt, and the religious corporations which sought to subject themselves to the severest privations, tried in vain to banish chloride of sodium from their food. Physiological experiments on animals show (Wundt, Rosenthal, Schultzen) that this salt is indispensable to the system, and serious consequences have followed its suppression. Physiological chemistry explains these facts by showing that chloride of sodium enters into the composition of nearly every part of the organism, and is especially indispensable to the constitution of the blood serum and cartilages. It appears to assist in the process of the nutrition of the tissues, and is indispensable to the formation of the bile, pancreatic and gastric juices. Cattle-breeders are well acquainted with the favorable influence produced on the development of animals by administration of chloride of sodium; without asserting that mixture of this salt with the food produces increase of growth and fat, we must admit (Boussingault) that animals fed in this way have more

glossy and thicker hair, a more healthy appearance, are more sprightly and active, etc.

Attempts have been made, but without success, to substitute chloride of potassium for the sodium salt; it has been found, however, instead of possessing the useful properties of the latter, to produce serious injury.1

2. The principal aliments are those furnished by the animal kingdom, that is the different forms of albumen, designated under the common name of proteine substances, and several other similar elements classed together under the name of caseines. All these substances contain Oxygen (O), Hydrogen (H), Carbon (C), and Nitrogen (N), besides a certain quantity of Sulphur (S) and Phosphorus (P), mineral salts, etc. They also contain, probably, iron in small quantities, though this is not yet proved in all cases.

Some vegetable products supply the same aliment, such as gluten or vegetable fibrine, which is found in many seeds, particularly cereals; vegetable albumen, found in emulsive seeds and vegetable juices, and legumine or vegetable caseine, found in large quantities in the seeds of leguminous plants. These substances may all be classed under the name of albuminoids. The transformations undergone by the albuminoid substances contained in plants bear a striking resemblance to those which take place in the animal economy, and which we shall proceed to examine. During the germination of seeds, the albuminoid substances contained in plants give rise to digestive ferments bearing the essential features of some of the ferments furnished by the animal organs. Thus the diastase produced by the germination of cereals, closely resembles the fermentation which we shall see takes place in the saliva and in the pancreatic juice.

3. Next come the ternary, non-nitrogenous (or non-azotized) principles containing (C), (H), and (O), in the proportions required for the formation of sugar, starch, dextrine, gum, and various mucilages; all of these substances are incapable of directly forming globules, the prevailing matter of which is nitrogen. These substances are derived chiefly from the animal kingdom; they are also found in animal food, but in very small quantities. Sugar is found in milk, in the liver, and in the blood which flows from this organ; it has been discovered

See Cl. Champy, "Étude comparée de l'Action Physiologique des Sels Potassiques et Sodiques et de leurs Chlorures." Strasbourg, 1870, No. 290.

Thèse de

in many epitheliums: in that of the cerebral ventricles are found white granules, some of which, in their behavior with the reagents, resemble amylaceous matter, and others dextrine; sugar also exists in the muscles and accumulates when they are not in action (as after long repose; after section of the motor nerves, and in the muscles of the fœtus), (Rouget). The integument of the non-vertebrated animals is formed of a glycogenous substance: this is the chitine of insects, the tunicine of the tunicata (animal cellulose), (Carl Schmidt). These substances are transformed into sugar by boiling with potash (Berthelot, Rouget). All these classes of alimentary substances become capable of being absorbed by contact with the digestive organs.

4. The last class of alimentary substances is the fats; these do not require to be digested, in the proper sense of the word; that is to say, the digestive juices produce no change in them; the fats are unchanged. They may, even, be absorbed by other surfaces than those of the digestive organs, as by the skin, for instance; we know that if fatty substances be rubbed on the skin, they will penetrate the epidermis: this is the only possible mode of nutrition by means of the external integument. The fatty substances are found in both the animal and vegetable kingdom.

Thus we see that nourishment may be derived, almost indifferently, from either the animal or vegetable kingdom: the amylaceous, glycogenous matters, forming almost the essential element of vegetables, are also found in animal products; thus we know that some savage tribes make fermented liquors (alcohol) with the sugar found in mares' milk. We have an instance, on the other hand, of an aliment which is apparently and essentially animal, though found in the vegetable kingdom: in the cheese which the Chinese make from legumine (caseine) derived from the fruit of leguminous plants.

It is especially important, however, to remark that the property of forming some of these substances does not belong to vegetables only, to the exclusion of animals: the formation of albuminoid substances evidently belongs to both kingdoms; the discovery of animal glycogeny (C. Bernard) proves that animals, as well as vegetables, can and do naturally form amylaceous substances, and the same is true with regard to fatty substances: we owe to experiments by F. Huber, Milne-Edwards, and Dumas, the knowledge of the fact that bees, fed exclusively on sugar, still possess the