BODY TISSUES AND FLUIDS 451 



by Bergeim, by analyses made upon the serum or plasma. The serum nor- 

 mally contains 9 to 11 mg. of Ca per 100 c.c. in the healthy adult, also in 

 infants. In advanced nephritis with acidosis and phosphate retention Mar- 

 riott and Howland(a) have found the calcium of the serum to be mark- 

 edly lowered, figures as low as 2 to 4 nig. More than ten years ago \V. G. 

 Macallum and Yoegtlin recognized the reduction in the calcium content of 

 the blood following the removal of the parathyroids in animals and the de- 

 velopment of tetany. The symptoms of tetany were found to be relieved by 

 the administration of calcium salts, llowland and Marriott, and more 

 recently Denis and Talbot, have shown that the calcium content of the 

 blood (serum) is greatly reduced in infantile tetany, falling to 2 to 3 mg. 

 in some extreme instances. Rowland and Marriott have shown that cal- 

 cium administration produces a prompt effect upon the course of the 

 tetany. In a few hours the spasmodic symptoms disappear. The calcium 

 treatment must be continued, however, for a long time. Calcium chlorid 

 administration causes an increase in the calcium of the serum coincident 

 with the cessation of symptoms, although, in most instances, the calcium 

 of the serum does not return to quite normal figures. Howland and Mar- 

 riott point to the prompt improvement in infantile tetany after calcium 

 medication and the absence of symptoms when the calcium of the blood 

 remains above 7.5 mg. as strong evidence of the role that calcium plays 

 in the production and dissipation of symptoms. Both Howland and 

 Marriott, and Denis and Talbot have observed some decrease in the blood 

 calcium in rickets, while Hess and Killian have noted a reduction in some 

 cases of scurvy. It is a matter of clinical observation that in fractures 

 occasionally cases are encountered which very rapidly regenerate bone, 

 while others do so very slowly. It is natural to link this with deviations 

 in calcium metabolism, but a few unpublished observations made in the 

 writer's laboratory on patients of Drs. Albee and Moorhead have failed to 

 disclose abnormal figures for the calcium of the serum. 



Magnesium. The normal magnesium content of the blood of both adults 

 and children (as Mg generally falls between 2 and 3 mg. per 100 c.c. 

 of plasma or serum, although with pathological bloods a somewhat wider 

 range of 1 to 4 mg. is found. A considerable number of different patho- 

 logical conditions have been studied, but the findings differ very little 

 from those found during health and do not appear to be characteristic 

 of any special pathological condition. 



Iron. As already pointed out, iron is present in hemoglobin to the 

 extent of almost exactly one-third of one per cent, which would make the 

 content of normal human blood about 50 mg. per 100 c.c. calculated as 

 Fe. Pathologically, it varies directly with the hemoglobin content. Iron 

 does not appear to be present normally in the plasma. 



Chlorids. Some of the observations recorded in the literature give 

 the chlorid content of whole blood, others the content of the plasma or 



