432 VICTOR C. MYERS 



hemoglobin table of Williamson above, the red cell count is very high at 

 birth, reaching 7 million in some instances, but drops to a fairly constant 

 level after the sixth to the tenth day. Owing to the diminished oxygen 

 tension at high altitudes the number of red cells is increased to maintain 

 the oxygen carrying capacity of the blood at a normal I'-vrl, the number 

 being raised to 7 to million in extreme instances. A K-lative increase 

 in the number of red cells, or relative polycythemia, may occnr as result of 

 sweating, diarrhea, etc., while an absolute polycythemia is occasionally en- 

 countered, particularly in congenital heart disease and in Osier's disease. 

 The number of leucocytes normally varies between 3.000 a nd 10,000 per 

 cubic millimeter, although figures between 5,000 and fi.OOO are the most 

 often encountered in a fasting condition. The leucocytes are subject, to 

 greater physiological variation than the red cells, but considering their 

 much smaller number in comparison with the red cells, these variations 

 have little influence on the chemical composition of the blood as a whole. 

 In the leueemiaSj however, the leucocyte count may rise to 000,000 and 

 even higher. With such a marked leucocytosis, and consequent leucolysis, 

 the uric acid content of the blood may be greatly increased. Although the 

 blood plates are normally regarded as amounting to from 200,000 to 500,- 

 000 per cubic millimeter, on account of their small size. 3 u, their variation 

 is apparently without influence upon the chemical composition of the blood. 



Blood Nitrogen 



Total Nitrogen. The total nitrogen content of perfectly normal blood 

 amounts to somewhat more than 3 per cent. Of this. ('. per cent is de- 

 rived from the various proteins of the blood, about three-quarters being 

 from the cellular constituents, chiefly the hemoglobin, and one-quarter from 

 the plasma proteins, albumin, globulin and fibrinogen. The hemoglobin is 

 obviously the most important as well as the most variable contributor to 

 the total nitrogen. In pernicious anemia the total nitrogen may be re- 

 duced to considerably less than half the normal figure, while in severe 

 nephritic the nitrogen content is frequently very low. 



Non-protein Nitrogen. Although the non-protein nitrogen normally 

 constitutes only about one per cent of the total nitrogen of the blood, never- 

 theless greater interest is attached at the present time to variations in the 

 bodies which form the non-protein than the protein nitrogen. This is due 

 largely to the fact that the variations in these non-protein constituents 

 give tis an insight into some of the processes of anaboli>m and catabolism. 

 The food nitrogen is carried by the blood to the various tissues and the 

 waste nitrogen to the kidneys, directly or indirectly by the same medium. 

 After a meal containing protein there is a temporary elevation in the 

 non-protein and amino nitrogen of the blood. In diseases of the kidney 



