The theory of Baron Liebig concerning the change which the blood experiences in color, in its passage through the lungs, meets with the approbation of many physiologists, although there are some important difficulties in the way of fully receiving it. A chemical analysis of the blood shows it to be composed of albumen and fibrin, together with some other substances, in small proportions, and always perceptible traces of iron. He attributes the change in color to the iron, as this substance enters into combination with carbon and oxygen. For, as the blood passes through the trunks of the larger vessels and capillaries, it receives the carbon from the tissues which are continually transformed, and taking up the oxygen from the arterialized blood, forms carbonic acid, which unites with the iron, forming proto-carbonate of iron. This being of a gray color, he supposes it to be that which, with the other impurities of the blood, gives the venous blood the dark blue color. Then, as the blood comes in contact with the oxygen, as it is returned and exposed to this element in the lungs, the carbonic acid leaves the iron, which has a stronger affinity for oxygen than for carbonic acid, and forms the scarlet red peroxide of iron, that gives the characteristic color to the arterial blood. After this, as the blood is sent out through the smaller arteries and capillaries, it again gathers carbon and other impurities from the system, and becomes the dark, venous blood, thus completing the whole change of color in the circulation.
L.
As already mentioned, different articles of food have been divided into the azotized and non-azotized, or those which contain nitrogen as one of their constituents, and those which are nearly destitute of it. Of these, according to Liebig, the azotized portions are simply to supply the waste that is continually going on in the body, and promote its growth in the early stages of existence, or, in other words, the nutrient portion; while the sugar, starch, &c., are mainly of use in the respiratory organs. The correctness of this view may be understood from the fact, that the inhabitants in the colder regions of the earth consume a much larger quantity of oil and fat than the residents of hotter climates; and also those dwelling in the temperate zones can eat with greater impunity a larger quantity of fat meats in the winter than in the summer, there being then so much more demand for animal heat than in the summer.
M.
The suggestion of using the bellows in asphyxia, is from the directions of that distinguished and veteran surgeon, Valentine Mott, of New York city. The directions in the first part of the paragraph are the most practical, and best adapted to the wants of the community.
GLOSSARY
Ab-duc´tor. [L. abduco to lead away.] A muscle which moves certain parts, by separating them from the axis of the body.