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HENRY A. MATTILL AND HELEN I. MATTILL 



P, and higher in Na and Cl than the striated muscle. Since the K and 

 P content of muscle is greater than that of the surrounding fluids, blood 

 plasma and lymph, they conclude that the fibers of muscle are not sur- 

 rounded by a semipermeable membrane, but that most of the water and 

 of the K, P, S and Mg in the tissue is held in colloidal combination in a 

 non-diffusable form. Many of the ductless glands are characterized by 

 their rather marked content of one of the mineral elements in organic 

 combination, as the spleen by iron, the thyroid by iodin and bromin 

 (Labat), the hypophysis by P, the thymus by arsenic (Diesing). 



Weil has recently studied the mineral constituents of human nervous, 

 tissue (Table III). If the concentration of these elements in the fresh 

 nerve substance is considered, there is a rather interesting classification into 

 two groups, the first of which, comprising Ca, Mg, P, S, Cl, shows wide 

 variations in concentration, and the second of which, including Na, K, 

 and Fe, maintains about the same concentration in the different nerve 

 tissues. In view of the effect of the Ca concentration on irritability (see 

 p. 336) it is interesting to note the lower concentration of Ca in gray 

 matter. If the analyses are calculated to a water-free basis the conditions 

 are reversed, the concentration .of the first group is nearly constant, of 

 the second group variable. 



TABLE III 



The understanding regarding the mineral constituents of the blood 

 is even less satisfactory, and is subject to greater confusion than is that 

 of the organs because in addition to the application of unsatisfactory 

 methods, there has been confusion as a result of subjecting only a part 

 of the blood, as the serum, the red blood corpuscles or the plasma, to analy- 

 sis. Recent work is bringing order out of this chaos, with the result that 

 the blood is coming to be looked upon as that constituent of the body show- 

 ing most constant composition with respect to mineral constituents, under 

 normal conditions (Table IV). From this it is not to be concluded that 



