Among the unsolved questions of medicine are the relationship of obstruction of the bowel to the development of serious symptoms of shock; the exact relationship of putrefaction in the bowel to the onset of various degenerative diseases; and, particularly, the control of infestation of the intestines by worms - conditions which are extremely common in tropical and oriental countries but which are now beginning to be found with increasing frequency in this country.

The Blood. Long ago it was recognized that the blood is one of the most important constituents of the human body, that it is the fluid which gives life to the tissues, that it takes from the tissues their waste products and conveys them to the organs of elimination, and that it is largely concerned with the ability of man to resist disease and to overcome damage to his body. Not, however, until the microscope was invented did scientific medicine begin to have any clear conception of the constituents of the blood. This fluid represents roughly from one thirteenth to one-twentieth of the body weight. It is far more than a fluid; it is a suspension containing many ingredients in the shape of formed and of dissolved elements which have an intimate bearing on life and health.

Metchnikoff conceived the idea that the white blood cells were the important element for attacking infectious disease. He gave to them the name "phagocyte,"with the idea that they ate and digested cells. However, the white blood cells represent but one of the types of formed elements in the blood. There are in addition, the red blood cells and the platelets. The white blood cells number about 5,000 to 7,000 for an amount of blood about the size of a pinhead (1 cu. mm.). The red blood cells number from 4,500,000 to 5,500,000 for the same quantity. The blood platelets average from 150,000 to 250,000 for the same amount. Unquestionably all of these constituents have special functions, some of which have begun to be understood; but about many of their functions there is still a great deal of doubt.

The red blood cells seem to be charged primarily with the conveying of hemoglobin around the body. The hemoglobin contains iron and is concerned with the distribution of oxygen. If the hemoglobin is lessened in amount, there is less oxygen carried, and the blood becomes exceedingly pale. The normal amount of hemoglobin is listed at 100 per cent, but a person may have anywhere from 50 to 70 per cent and still feel fairly well. If the hemoglobin drops much below this amount, one is likely to indicate the deficiency by shortness of breath. The pallor associated with lack of hemoglobin is typical. There are many conditions in which the hemoglobin is altered or destroyed so that it cannot carry oxygen. For instance, in poisoning with carbon monoxid gas the hemoglobin is changed to a form which cannot carry oxygen, and the person becomes purple.

In the condition known as pernicious anemia there is a deficiency in the number and a change in the character of red blood cells. A lessened number of cells may be due to the fact that they are being destroyed too rapidly or to the fact that they are not being created sufficiently rapidly and in sufficient quantities. In pernicious anemia, their number decreases so rapidly and stays so low that it threatens life itself. The number of red blood cells may fall to 1,000,000 or 1,200,000, instead of the 4,000,000 to 5,000,000 that represent the normal condition.

One of the greatest finds of recent times was the discovery that the liver contains a substance which has the specific power of raising the number of red blood cells, apparently by stimulating the production of red cells in the places in the body where they are produced, notably in the bone marrow. Concentrated extracts have been developed which cause rapid formation of the cells; and a fatal termination to pernicious anemia, which was formerly inevitable, is no longer feared. Moreover, continued investigation now shows that there are substances also in the wall of the stomach and in the muscles which have this specific power.

Obviously, only the frontier of this unknown land has been invaded. Much more needs to be known as to the nature of the red blood cell, its method of formation, the materials from which it is formed, and the factors governing its formation, growth, and destruction. It probably has something to do with the ability of the body to resist the invasion of foreign substances. At all events, the red blood cells can be sensitized in such a way that they will clump together or will dissolve when certain substances of bacterial or other foreign origin are injected into the body; and obviously, if such reactions occur, the result to the patient's health and life is serious. The materials used in the treatment of pernicious anemia must also be investigated more thoroughly, and their functional ingredients determined. Already one can take a concentrated powder instead of eating large quantities of raw liver; and at least one liver extract is being prepared as a pure chemical.

The knowledge of the platelets in the blood is even more recent than that of the red cells. These platelets are seen only with great difficulty, and can be counted only by special technics which have been developed, none of which is of any great accuracy. The platelets are concerned with the ability of the blood to clot promptly when it escapes from a blood vessel. It is difficult to conceive of anything more important to a person's life than the ability to stop bleeding. Because of the importance of this reaction, nature has apparently developed a number of effective mechanisms. The blood contains a substance called fibrin, which is concerned in the formation of the clot. Unquestionably in association with the fluid constituents of the blood other materials may be involved. Most physiologists believe that the platelets have a prominent activity in this direction.