For convenience, I limit the hygiene of pregnancy to the preservation of the health of woman during those periods of her life beginning with conception and terminating with the commencement of labor. This is an arbitrary limitation, for it cannot be technically asserted that pregnancy is concluded until the womb is completely evacuated of fetus and secundines. It excludes also the diseases of intrauterine life. The preservation of the health of the mother so constantly and directly refers to the health and life of the fetus that it must necessarily follow that the hygiene of pregnancy will comprehend, to a certain extent, the hygiene of the fetus; but only so far does it relate to the diseases of intrauterine life.

The changes, consequent upon pregnancy, which take place in the general organism, glandular system, and generative organs are physiological. Pregnancy is not a disease, yet the laws of diagnosis have, as yet, failed to define the limit where the physiological ceases and the pathological begins. The structural changes and formative activity establish conditions susceptible of easy, and sometimes rapid and insidious transformation into morbid processes. They invite and present the opportunity for the detrimental influence of trivial and extraneous agencies. It is not, therefore, surprising that the acquired causes of the diseases of pregnancy should be numerous and multifarious.

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The virgin uterus measures but sixteen square ficial area, the pregnant womb, at term, three hundred and forty. The textural changes which take place, involve every constituent tissue of the organ. The constantly increasing superficial area, weight, and dimensions of the pregnant womb take place in a cavity supposed in a normal condition to be always full. This cavity is inclosed, for the greater part, with walls possessing great expansile and elastic properties; nevertheless, especially in primiparæ, the mechanical disturbances of its contents are manifold and, oftentimes, serious. The cavity is filled to repletion and its walls stretched to their utmost tension. The neighboring viscera are displaced and compressed. The move ments of respiration are interrupted. The thorax is diminished in depth and increased in breadth. Vital capacity is lessened. The portal circulation is disturbed. The arterial and venous

blood currents in the vessels in the abdominal cavity and lower

extremities are obstructed; as a consequence there is "superior arterial hyperemia and inferior venous hyperemia (Barnes)." Thus local congestions may be determined. The complex processes of digestion, nutrition, and elimination, in some one or more respects, may be impeded, impaired or perverted. The peristaltic movements of the intestinal tract are so constantly lessened with the increasing volume of the uterus that constipation, more especially during the later months of pregnancy, is a common and troublesome complication. In consequence of the diminished capacity of the bladder, micturition is more frequent and annoying. These disturbances of the functions of the organs and anatomical relations of the parts, caused by the presence and continuous growth of a vascular and highly organized tumor in a closed cavity, lined by an acutely sensitive membrane, stretched in various parts to its utmost tension, would seem to present a variety of conditions favorable to the development of disease. This danger is vastly augmented by the constantly increasing afflux of blood to, and the exaltation of nutritive and formative activities in, the uterus and genitalia. The changes which take place in the constitution of the blood approach, even more closely, pathological conditions. The red corpuscles, albumin, iron, and salts are diminished. The white corpuscles, fibrin, and water are increased. With the increase in volume there is increasing impoverishment of the blood and loss of the carriers of oxygen. Consumption and waste, and elimination of carbonic acid and urea are angmented with diminished ingestion and assimilation of food. and metamorphosis are consequently deranged. crease of water and fibrin, and loss of albumin, a condition of scrous plethora and hyperinosis is established, which favors transudation, coagulation, and thrombosis.

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Not less important are the dynamic changes in the circulation. With hypertrophy of the heart, there is dilatation of its cavities and increased arterial tension. It may be that these dynamic changes are compensatory and not resultant. For they coexist with lessened vital capacity, diminished oxygenation, increased blood mass, blood degradation, and hyperinosis with increased liability to coagulation.

These blood and circulatory changes begin and progress consentaneously with the nutritive and developmental pro

cesses taking place in the generative organs. With the rapid growth and increasing demand of the new being for sustenance, there is progressive waste with lessened food supply. With the augmentation of blood mass there is anemia, diminished oxygenation, and increased propulsive power of the circulatory apparatus.

The changes which take place in the glandular system are equally interesting and no less remarkable. Probably all the glands undergo some change, due, perhaps, to the increased work imposed upon them. The thyroid gland and spleen are usually enlarged, the latter sometimes very much so. The thyroid enlargement may have some connection with the hypertrophy of the heart and increased arterial tension. The condition of the spleen would seem to be directly connected with the blood changes. They may be conservative processes, but are closely allied to certain pathological conditions.

The most notable gland changes are those which occur in the secretory and excretory glands. The salivary glands, the glands of the uterine neck, the sebaceous and sudoriparous glands, and those of the stomach, all, to a greater or less extent, varying with individual peculiarities and susceptibilities, undergo functional and organic change. These modifications of gland structure and function may be the physiological outgrowths of the circulatory disturbances, increased nerve irritability, and extraordinary activity of the nutritive energies. Turgescence is a common factor, and increased secretion a common result. They are probably eliminative and compensatory conditions, but why should they vary so much in different women, and in the succeeding pregnancies of the same woman without apparent cause? As a rule, the increased secretions are simply the physiological result of glandular activity. Excessive salivation, uterine hydrorrhea, and the vomiting of unusual quantities of fluid must, however, be considered pathological.

The changes which take place in the mammary glands are developmental. Milk is the natural aliment of young animals. Maternal lactation is the natural method of supplying it to the infant. The secretion of milk is the ultimate product of those changes in these glands, which begin with pregnancy and are completed during the earlier days of the puerperium. Lacta

tion begins with birth of the offspring, and continues for an indefinite period. The function is not suddenly established, nor does it suddenly subside. The periodical evolution of the breasts corresponds with the progress of pregnancy. Both processes are gradual. The gradual subsidence and cessation of the function of milk secretion should correspond with the gradual involution of the gland structure and its return to a state of quiescence and diminished size. With the recurrence of pregnancy the process of evolution and functional activity is re-awakened. No other organs of the body, except the uterus and ovaries, are subjected to similar periodical changes. As the uterus and ovaries, so likewise the mammary glands, when the period of sexual involution begins, undergo those changes which finally terminate glandular activity. The processes of periodical evolution and involution are in inverted parallelism. The former is as necessary to promote the secretion of milk as the latter is to restore the gland to a normal quiescent condition, to await rehabilitation and renewed functional activity with succeeding pregnancy. To the functional irregularities and derangements caused by artificial interference with these physiological processes must be traced many of the tumor diseases to which these glands are so liable.

Several years ago, when engaged in the study of the diseases of the lymphatic system, I suggested that the cicatrices and pigmentations of pregnancy were due to disturbances of the lymph spaces. Subsequently, I demonstrated that the cicatrices were dilated lymph spaces of the corium. Since then Creighton has verified my suggestion in regard to pigmentation. These pigmentations are due to the deposition in the lymph spaces and other lymph structures of the waste products of evolution. The discoloration of the areola of mammary glands is one of the earliest signs of the evolution, and the latest to disappear in the involution of the glands. It is the result of the deposit of pigment granules in the connective-tissue spaces. Granular pigmented cells are also found within the secretory acini and in the lymph spaces of the subjacent lymphatic glands. The pigmentations in other localities are, probably, similar depositions of the waste products of tissue changes taking place in adjacent and neighboring parts.

The lymphatic structures of the mammæ are essential ap

pendages of the secretory apparatus of the glands; and in the breasts, as elsewhere throughout the body, are the receptacle of the redundant elements and products of nutrition. The absorption and disposal of these products and their elaboration and utilization are the special functions of the lymphatic system. These processes are very active during pregnancy.

Physiological leucocytosis is one of the characteristic phenomena of pregnancy. Virchow' was the first to call attention to the fact that these periodical excesses of white corpuscles in the blood were not due to changes taking place in the blood itself. They are mainly the product of irritation of the lymphatic glands. He says: "In proportion as pregnancy advances, as the lymphatic vessels of the uterus dilate, and the interchange of material in the organ increases with development of the fetus, the lymphatic glands in the inguinal and lumbar regions become considerably enlarged, and sometimes to such an extent that, if we were to find them in a similar state at any other time, we should regard them as inflamed. This enlargement conveys into the blood an increased quantity of fresh particles of a cellular nature, and thus from month to month the number of colorless corpuscles augments." The lymphatic structures of the pelvic region must be the chief source of the leucocytosis of pregnancy; but with Creighton' we "must believe that the abundant cellular waste products of the breasts contribute to that condition."

The disposal and utilization of the unused and waste products of secretion is one of the marvellous phenomena of pregnancy. The lymphatic system is the laboratory in which these materials are re-prepared for future nutrition. The increased burden imposed upon it excites new and augmented activities. It seems to occupy the relation of an intermediary, completing the physiological processes and protecting the organism from pathological conditions. But as organs of reception, filtration, elaboration, and conveyance, the lymph glands and structures may become foci for the generation and diffusion of disease.

The liver and kidney have increased work to do during pregnancy. Trousseau and several other observers have insisted that the liver was enlarged. It supplies the bile which is an 1 "Cellular Pathology," p. 224.

"Physiology and Pathology of the Breast."