THE RELATION OF DIET TO DISEASE 429 
withdrawn from the bones ; and there is much proof that 
during the daily metabolism a certain slight movement of 
phosphorus takes place. The metabolized phosphorus is 
excreted by carnivores practically from the kidney alone ; 
by herbivores almost entirely through the intestinal wall, 
Avhile in the omnivores it is excreted by kidney and intes- 
tinal tract. Whether these facts have any real influence 
on the phosphorus need of different types is not alto- 
gether determined. 
Calcium also enters into many of the essential func- 
tions of life, coagulation of the blood, contractility of the 
heart, etc. Omnivorous diet is usually deficient in this 
element, which is very irregularly distributed both in 
animal bodies and plants. Insufficient amounts lead to 
deprivation of body tissues and to the production of 
osteomalacia-like conditions. Voit produced marked thin- 
ning of the skull bones and sternum by a diet poor in 
calcium. Steenbok and his associates had the same 
results in cattle by feeding '' shorts " a diet rich in mag- 
nesium. Etienne (4) showed that an excess of magnesium 
in an otherwise well balanced food caused a continual 
loss of calcium. Adults stand a deprivation of calcium 
much better than children or young animals. They often 
show no symptoms and retain a normal blood content as 
the losses from the blood and soft tissues are promptly 
replaced from the bones. Sooner or later all these 
animals show weakness and flexibility of the bones. 
Osteomalacia occurred in 5.2 per cent, of the animals on 
an omnivorous diet, that is this number showed gross 
evidence of absorption of bone salts. This condition 
occurring in man and the lower animals is a generalized 
softening of adult bones that were at one time normally 
calcified. Three clinical varieties are recognized in man : 
a mild form seen in pregnant, puerperal and lactating 
women, a senile form in which the lesions are usually 
limited to the peMs, and a severe progressive form 
(4) Jour. Physiologic et Path., Vol. 14, 108, 1912. 
