(34 PHYSIOLOGICAL ROLE OF MINERAL NUTRIENTS 



IMPORTANCE OF LIME SALTS FOR ANIMALS. 



In animals lime salts are necessary, not simply for the formation of 

 the bones but also for every part of the body, and they are required 

 for the lowest forms as well as for the higher animals. 



The action of the heart is above all most intimately connected with 

 the presence of lime salts. Thus a frog's heart will soon stop even in 

 a physiologic salt solution (0.6 per cent sodium chlorid), but will con- 

 tinue to beat when some ash of blood is dissolved in the same solution. 

 Ringer has shown that a good circulating fluid for the heart may be 

 compounded by preparing a mixture of such salts as normally occur in 

 the blood. In such a solution the isolated frog's heart will beat almost 

 as long as it would in detibrinated blood. Halliburton" says: "The 

 necessity for lime salts is especially great. In fact, the close adhesion 

 of proteids generally with small quantities of mineral matter is rathei 

 suggestive of combination than mere mixture. Lime salts adhere 

 especially closely and in fact seem indispensable for many of the func- 

 tions of the body, of which the beating of the heart and the contraction 

 of skeletal muscle arc good examples. Blood from which the salts 

 have been removed keeps the heart going, but the tracing is abnormal, 

 resembling that produced by a weak solution of a lime salt. It is in 

 fact found that dialysis will not remove the lime from serum albumin, 

 though it removes the greater part of the sodium and potassium salts." 



The great importance of calcium salts for the various organs uf ani- 

 mals is also illustrated by the empirical knowledge gained by physi- 

 cians. Thus a prominent medical work'' states: "Calcium chlorid is 

 used with benefit as an internal remedy in the various manifestations 

 of the strumous diathesis. It often causes the resolution of glandular 

 enlargements and the calcification of tubercular deposits, aids the 

 cicatrization of ulcerating cavities, and has proved curative in eczema 

 and lupus. It is highly praised in phthisis, also in chorea, and for the 

 colliquative diarrhea of strumous children. In solution used exter- 

 nally as a fomentation it is said to hasten the maturation of boils. '' In 

 direct contact with the heart, however, this salt is not harmless, as 

 shown by the experiments with a frog's heart. Probably a hydrolytic 

 dissociation, with liberation of hydrochloric acid, however slight it 

 might be, brings on the injurious effect. 



Munk c observed during the inanition of men and dogs a gradual 

 increase of the lime secreted in the urine. Katsuyama'' noticed in 

 observations on starving rabbits in the first four days a gradual decrease 

 and afterwards a slow increase of lime in the urine, while there was a 



«Chem. Physiol., London, 1891, p. 256. 



6 O. L. Potter, Handbook cf Materia Medica, Pharmacy, and Therapeutics, Phila- 

 delphia 



c Suppl. zu Virchow's Arch., Vol. CLI. 

 ^Zeitschi f. Phys. Chetn., 1899, Vol. XXVI. 



