62 THE INDIVIDUAL ORGANISM 



normal intercellular substances that form the bulk of cartilage and bone and bind 

 the cells of other tissues together. Capillary bleeding is one of the characteristic 

 symptoms of ascorbic acid deficiency and is explained by failure of the intercellular 

 binding material, with resultant rupture of the capillary walls and leakage of 

 blood. This vitamin is necessary for normal tooth and bone formation and for the 

 maintenance of healthy gums in man. Pronounced deficiency results in the disease 

 called scurvy, the symptoms of which include redness, swelling, and bleeding of 

 the gums, which eventually become thickened and retracted, and in severe cases 

 the loosening and shedding of the teeth. Capillary fragility is marked, with hemor- 

 rhages occurring in the skin; the flesh bruises easily, and wounds are slow to heal. 

 Scurvy has a long record in medical history as one of the to-be-expected horrors 

 of sieges and prolonged voyages. The English, long before vitamins were heard 

 of, found that fresh fruit and especially lime or lemon juice added to the navy 

 rations would prevent or minimize scurvy. 



This completes the list of vitamins known to be essential in human nutrition. 

 However, there remain many others, some of which may prove to have this 

 status. Besides the fat-soluble vitamin E, already mentioned, the following 

 water-soluble vitamins are being investigated from this standpoint: pyridoxine 

 (vitamin B 6 ), required in the diet of all laboratory animals studied but not proven 

 essential for man, and concerned in the maintenance of normal skin function, 

 hemoglobin synthesis, and muscular coordination; pantothenic acid, required for 

 the growth of many bacteria, and deficiency of which in laboratory animals 

 causes changes in hair color, adrenal and digestive malfunctioning, and many 

 other disorders; inositol, a necessary growth factor for some yeasts, which has a 

 wide variety of effects in laboratory animals; paba (para-aminobenzoic acid), 

 which reverses the bactericidal action of sulfanilamide and appears to affect 

 hair color and milk production in rats and growth in chicks; biotin, lack of which 

 produces a characteristic group of effects in rats, usually ending in death, and 

 which is present in unusually high proportion in embryonic cells and in skin 

 tumors; choline, especially concerned in fat metabolism, and considered by some 

 students a food rather than a vitamin because, like inositol, it is used in amounts 

 much larger than the minute quantities required of most vitamins; the vitamins 

 P (citrin, rutin), which seem to affect capillary fragility in some way different from 

 the action of ascorbic acid; and vitamin B i2 (animal protein factor), unusual in 

 that its molecule contains cobalt, and strongly suspected of being involved in 

 the prevention of pernicious anemia. Still others might be mentioned. 



Inorganic materials. Besides proteins, fats, carbohydrates, and 

 vitamins, the body requires a number of inorganic substances. Chief 

 among these is water, which is an essential part of protoplasm and all 

 body fluids, and makes up over 70 per cent of the weight of protoplasm 

 and about 57 per cent of the body weight. 1 It is also the solvent and 

 carrier of excreted wastes and is evaporated in the maintenance of proper 



1 Of all the water in the body, about 5.5 per cent is in the blood, some 25 per cent 

 in the extracellular tissue fluids, and the rest in the protoplasm. 



