Just as all chemical substances are made up of molecules, all organisms are composed of histologic units called cells. In all mature tissues there is also more or less intercellular substance. The fibres of fibrous and muscular tissues are altered cells. As a general rule, tissues derived from hypoblast and epiblast, retain the cellular organization, while most of the mesoblastic tissues loses it. Bone contains mineral matters (salts of calcium, etc.) which have infiltrated the cells and have been deposited between the cells. Enamel of teeth has almost entirely mineral constituents. The attempt has been made to distinguish organic from inorganic tissues, but all tissues are essentially and originally organic, though there are marked differences in degree of infiltration of inorganic matter. Adipose tissue is areolar fibrous tissue in the meshes of which fat has been deposited. The deposition of glycogen in the cells of the liver, spleen, muscle, etc., is not essentially different, but glycogen is never deposited so permanently, nor in such large masses as to give its name to a tissue. Cartilage consists of an intercellular matrix containing relatively few cells. The matrix, which is a secretion from the cells, is composed of chondrin, which is a mixture of mucin and gelatin. Some organisms, such as amœbæ (animal) and bacteria (vegetable) consist only of a single cell. The typical cell is a mass of protoplasm surrounded by a cell-wall and containing a portion of special vitality called the nucleus. Within the nucleus may be found one or more centers of activity called nucléoli. Animal cells are more apt to be atypical than vegetable, so that many active animal cells possess no distinct cell wall, and many, of which the red blood corpuscles are the principal example, have no nuclei. Nucleoli are often undemonstrable. Fibres are known to represent altered cells only by tracing them through the various stages of development. No satisfactory definition of protoplasm can be given. It is the material of which cells are composed, and is a highly complex union of C, H, O and N, with other less important elements. Its exact constitution varies in different cells, and especially in different organisms.

CHAPTER II.-CHEMISTRY.

The human body is composed of fifteen elements, which may be arranged in three groups:

I. C, H, O, N compose 97 per cent of the entire body.

3. S, P, Cl, Si, F, I are the non-metals of the body.

Small amounts of other elements, such as Cu, Zn, Li and As may be present from medication or accidental introduction, without doing harm, but also without forming part of the tissues.

C, H, O, N, S, P must enter the body in organic combination and any substance, in order to support life more than temporarily, must contain at least the first four in organic combination. Such substances are called proteids, because of first importance. C, H, and N, if introduced in the elemental state, do not enter into chemical combination in the body, and merely pass through the system as foreign substances. O is normally inspired in large quantities in the elemental form, and it combines loosely with hæmoglobin, and later combines more permanently in the formation of

waste matter, such as CO2. Probably little, if any, of O taken in the elemental form actually takes part in the formation of tissue. The other elements, if introduced as such, would readily form compounds, either inorganic and organic, and from these could be transformed into constituents of the tissues. It is obvious that practically very few of the elements

Each square in the diagram represents one per cent by weight of the human body. The percentages are only approxima e, water, pro:eids and fats, varying several per cent.

S

would be free from dangerous corrosive properties if thus introduced. and P, besides forming a necessary part of protoplasm, are also needed in the body in the inorganic form of sulphates and phospates, but it is extremely doubtful, whether in the latter form, these elements ever are assimilated into organic constituents of the body.

Proximate Principles are substances into which the body may be resolved (theoretically) without chemic change. In other words, they occur as such in the body. The proximate principle forming the greatest part of the body is water, which composes about two-thirds of the entire weight. Proteid matter composes about one-fifth of lean muscle. Calcium phosphate makes up about 60 per cent of bone. Sodium chloride occurs in the body to the amount of 120 grams, a quarter of which is renewed daily to compensate for loss by elimination. Hæmoglobin forms about 13.5 per cent of the blood, and from 5 to 15 per cent of muscle. The various fats form a considerable, and sometimes an enormous amount of the total weight remaining after the evaporation of water from the body. Other proximate principles will be referred to in connection with the organs in which they are produced, or of which they form important constituents.

With regard to the food on which they chiefly subsist, the higher animals are divided into herbivoræ, carnivoræ and omnivora. The herbivoræ possess the most highly evolved digestive tracts, their intestinal canals being very long in proportion to their size while they have two to four cavities corresponding to the single stomach of carnivora and omnivoræ. Carnivoræ and omnivoræ do not differ materially in the anatomy of the digestive organs, but the former have relatively shorter intestines and more. active stomachs, the secretion of the stomach being higher in HCI. Pigs and human beings are the most typical examples of omnivoræ, sheep and cattle of herbivoræ, the felines of carnivoræ. These classes of animals differ in no essential respect, but merely in the relative ability to digest and absorb preformed nutriment.

All higher animals store fat in areolar tissue, deriving it either from fat ingested as such, or probably from both carbohydrate and proteid matter. (See section on classification of foods.) In disease, the proteid matter of the body is broken down, and part of it is deposited as fat. Whether carbohydrates can be formed in the animal body from fats or proteids, is disputed. While the higher animals cannot produce organic matter from inorganic constituents, and cannot produce proteid matter at all, plants have the power of manufacturing all three classes of food, as well as other complex organic compounds, including many drugs, from inorganic matter. Excepting in seeds, and a few special parts of certain plants, plants contain proteid matter in very small proportion, so that only animals with complicated digestive organs, the herbivoræ, can extract a sufficient quantity of proteid to sustain life. Herbivoræ must eat enormous quantities of food, as compared with carnivoræ, and must spend a relatively longer time in eating. Carnivoræ prey upon the stored and concentrated proteid of other animals. Omnivoræ, by selecting parts of plants especially rich in proteid, can sustain life without eating flesh at all, but are best nourished by a mixed diet.

Plants do not form proteid and other nitrogenous organic compounds by using the atmospheric N, but by extracting inorganic compounds of ammonia and nitrites and nitrates from the soil. The electric effect of lightning causes atmospheric N to combine with Ọ and with other gases which may be present in the air. These compounds are washed to the earth in rain, and probably form the source of inorganic nitrogen compounds. In

the decay of organic matter, nitrogen compounds are again broken down by bacteria into inorganic ammonia, nitrites and nitrates. Carbohydrate matter is formed only by plants or parts of plants containing chlorophyl, (a peculiar green coloring substance), under the direct action of the sun's rays (or, experimentally, by similar actinic rays of electric light). Carbohydrates are formed by plants from CO2 and H2O. The general formula of carbohydrates being CmH2nOn, it is evident that, for every molecule of CO2 seized by the plant, two atoms of O are liberated. CO2 is formed by burning, and also by slow combustion in living cells, especially of animals. It is evident that, if there were only animals and plants without chlorophyl in the world, the atmosphere would gradually become surcharged with CO2, and that a balance tends to exist between animal and plant life. Prior to the carboniferous age, there must have been a gradual increase of CO2 in the atmosphere, in consequence of which vegetation was luxuriantly supported, while only sluggish animals could exist. With the clearing of the air, higher forms of animal life became possible, while the conditions were not so favorable to plant life. A few plants, such as Venus's fly trap, sundew, pitcher plant, etc., secrete juices similar to that of the stomach, and are partly carnivorous, but they also possess the ordinary vegetative methods of assimilation. Excepting the evergreens, cold weather prevents the action of plants in fixing the C of CO2 into carbohydrate matter, and this function is also in abeyance in the dark, and is not shared by plants lacking chlorophyl.

Catabolic Products. Since C, H and O form the principal part both of the animal tissues and of foods, it is evident that CO2 and H2O must be produced during oxidation. The chief catabolic product is CO2, of which about 1000 grams are formed daily in the human body. It is mainly eliminated through the lungs, but is also exhaled through the skin, and is found in all secretions and excretions. Only a small amount of H2O is actually. formed in the body, and this is indistinguishable from H2O introduced as such.

While CO2 and H2O are formed by the oxidation of all organic foods and tissues, nitrogenous food and tissues produce other waste matters. these, the chief is Urea, N2H4CO, of which the adult human being eliminates about 30 grams daily. Next in magnitude of the products of nitrogenous waste is Uric Acid, one-half to one gram being formed daily. Uric acid was formerly considered to represent incompletely oxidized matter, and to have essentially the same source as urea. It is now believed that uric acid is derived mainly from the waste of the nuclei of cells. The other products of nitrogenous waste are formed during muscular and glandular activity, but are mainly converted into urea by the liver before being excreted, so that they are found only in minute quantity in the excretions. Some of these intermediate products, notably Xanthin, are similar to the active principle of tea and coffee, and have a similar action in stimulating the nervous system. Normally, all but traces of nitrogenous waste matters are eliminated through the kidneys.

All metabolic substances of the body, except CO2, H2O, lactic acids and inosite (see muscles), cholesterine (see bile), and the simple digestionproducts of fats and carbohydrates, are nitrogenous.

(To be continued.)

I

Vesicular Degeneration of the Chorion.

BY CARL E. BLACK, M. D.,

JACKSONVILLE, ILL.

Surgeon to Passavant Memorial Hospital, and to Our Savior's Hospital.

Read before the 1899 Meeting of the Illinois State Medical Society, Cairo, III.

WILL present for your consideration an unusual case of that comparatively rare condition, "Vesicular Degeneration of the Chorion." Just how rare this disease is, no one has yet discovered. One author says that it occurred once in 20,000 labors, while another claims once in 2,000 labors.

I have asked twenty practitioners who have been in practice for at least twenty-five years, and have perhaps averaged fifty obstetrical cases each year, how many times they have seen molar pregnancy. One answered, "twice," and eight answered "once," making in all, ten cases in an estimated 25,000.

To say the least, "Vesicular Degeneration of the Chorion" is extremely rare, but when it does occur, gives us urgent conditions to be promptly met.

My case is as follows:

Mrs. D., aged 20 years, called on me November 9, 1897, stating that she had missed one menstrual period, and it was now time for the second, which had not appeared. Examination showed uterus to be about the size of a two-months' pregnancy, and as far as I could discover was normal.

For a number of years she had suffered from severe attacks of headache, accompanied by nausea and vomiting, which would come on suddenly and were accompanied by pain in the right side. She was just passing through one of these attacks at my first examination.

I heard nothing more of the case until a month later, when I was called to see her, with all the signs and symptoms of hyperemesis of pregnancy. There was constant vomiting with pain in the right side. She was unable to take food or even water.

Careful examination showed the right kidney to be markedly movable over a distance of about three inches, and very tender on pressure. Pressure on the kidney would cause severe nausea. After trying the usual plans for two or three days without the least benefit, I determined to anchor the kidney back into its proper place, hoping by that measure to overcome the nausea and vomiting. Patient entered Our Savior's Hospital at once, and the operation was made on December 17, 1897. Without dfficulty the right kidney was brought back, through a lumbar incision, to its proper place and anchored with silk-worm gut sutures. Within twentyfour hours the nausea and vomiting had entirely disappeared, and the patient was able to take food. On the eleventh day she was considered convalescent with the exception of the necessity of lying quietly in bed until the kidney had time to become firmly imbedded in its new position.

In the early morning of the twelfth day, December 29, 1897. I was called by telephone, the messenger saying that severe vaginal hemorrhage had set in.