450 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



As the following table (taken from Vierordt^^) shows, there is a marked 

 deficiency in the proportion of inorganic salts in the bones in rickets. 

 The proportion of the different salts seems to be quite the same as in 

 normal bone. 



More modern analyses^** show a relative increase in water and 

 magnesium, with a persistence of the normal ratio of calcium phosphate 

 and carbonate. ^^ Cattaneo®° finds the increase in magnesium to vary 

 in different parts of the skeleton, being greatest in the ribs. Aschen- 

 heim states that the blood of cliildren with rickets shows greater 

 variations from the usual CaO content (8-10 mg. per 100 c.c.) than are 

 found in normal children,^' which is not corroborated by others."' 



As an essential difference from osteomalacia is the fact that in 

 rickets there is a failure on the part of the osteoid tissues to calcify, 

 whereas in osteomalacia absorption of calcified tissue takes place with 

 subsequent substitution by osteoid tissue. Furthermore, in rickets the 

 deficiency in calcium is said to be present only in the bones, "^ whereas 

 in osteomalacia the soft tissues are also poor in lime salts. According 

 to SchmorP^ the first structural abnormality in rickets is a failure 

 to lay on calcium by small islands of cartilage in the zone of 

 preparatory calcification. 



None of the various hypotheses as yet advanced to explain this 

 defective ossification has satisfactorily accounted for all the observed 

 facts. That a deficiency of calcium in the food is the cause of rickets 

 is a most natural assumption, but it has not been proved that this is the 

 case. Young animals fed on calcium-poor foods show, naturally enough, 

 defective development of the bone,*''* but this differs essentially from 



^^ Nothnagel's System, vol. 7, part ii, p. 21. 



" Gassmann, Zcit. physiol. Chem., 1910 (70), IGl. 



^' The bones and muscles in Barlow's disease show quite the same deficiencj'' 

 in calcium as in rickets (Bahrdt and Edelstein, Zeit. Ivinderheilk.,il913 (9), 415). 



60 La Pediatria, VII, 497. 



8' Jahrb. Kinderheilk., 1914 (79), 446. 



"2 There is a decrease in the calcium of the muscles according to Aschenheini 

 and Kaumheimer (Monatschr. f. Kinderlieil., 1911 (10), 435) 



" Verhandl. Deut. Path. Gesell., 1905 (9), 248. 



6^ See Weiser, Biochcm. Zeit., 1914 (66), 95. 



