322 HENRY A. MATT ILL AND HELEN I. MATTILL 



content. The Ca in infant's blood increases during several months after 

 birth ; it reaches a maximum which varies but may be as much as double 

 that at birth, and thereafter there is a gradual decrease. Jansen in the 

 anulvsis of the blood of 33 men and women found an average of 12.46 

 ing. per 100 c.e^of whole blood at 20-30 years of age, 12.25 mg. at 30-40 

 years, 11;3 mg. at 40-50 years, and 10.05 rng. above 50 years. Dennstedt 

 and Rumpf found 11.6 mg. the average of many determinations on adults. 

 Usimr a nephelometric method Lyman(a) found about half this amount, 

 and slightly higher in women than in men. There is a difference of opinion 

 regarding the distribution of the blood Ca between the plasma and cor- 

 puscles, some (Larners) considering that all the Ca is in the plasma, 

 others (Heubner and Rona ; Cowie and Calhoun) that it is in both 

 plasma and corpuscles. Jansen found that if he washed the corpuscles 

 free from plasma with isotonic sugar solution they usually contained some 

 Ca (1-3.5 mg. CaO per 100 c.c. whole blood), but if they were washed with 

 hypotonic NaCl solution they were free from Ca, and he concluded that 

 the Ca is dissolved in a diffusible form in the corpuscles. Heubner and 

 Rona found a similar distribution between plasma and corpuscles in 

 cat's blood. The fibrin, Jansen found, contained 0.34 mg. CaO per 100 

 c.c. whole blood. The Ca content of the cerebrospinal fluid is about half 

 that of the blood and is less subject to fluctuations in pathological condi- 

 tions (Halverson and .Bergeim). 



The calcium content of the blood during pregnancy and lactation has 

 been the subject of considerable investigation because of the unusual drain 

 on body Ca at such times. During pregnancy and the puerperium Jansen 

 found an average of 12.5 mg. .CaO per 100 c.c., whole blood, a normal 

 value for the age. Lamers found 0.8-1 mg. higher CaO in pregnant 

 and lactating women, but he found high blood CaO in women 4-8 weeks 

 after delivery, regardless of whether they were lactating or not. Possibly 

 this illustrates the lag in adjustment after pregnancy which McCrudden 

 considers an explanation of osteornalacia (see p. 339). Lamers and Mul- 

 lik suggest that a rise in blood CaO causes the onset of labor. The in- 

 gestion of a Ca-poor or Ca-rich diet or of Ca salts seems not to affect the 

 blood Ca (Clark; Denis and Minot(fc)). 



The important role which the Ca ion plays in controlling the permeabil- 

 ity of colloidal membranes leads Briiikman(Z>) to the conclusion that the 

 Ca ion concentration of the blood is as constant at H ion concentration, and 

 that the distribution of the Ca in the blood between a protein compound 

 (25 per cent) and Ca (HCO 3 ) 2 and its ions (75 per cent) supplies the 

 necessary mechanism for its adjustment. Rona and Takahashi place 

 this Ca ion concentration at 30 mg. per liter of serum. The increased 

 blood calcium which has been found on subcutaneous injection or in- 

 halation of CaCL (Clark; Heubner and Rona) and which Yoorhoeve 

 claims to have found on ingestion of large amounts of Ca in food, cannot 



