374 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



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 only present 

 in the bones, whereas in osteomalacia the soft tissues are also 

 poor in lime salts. 



None of the various hypotheses as yet advanced to explain 

 this defective ossification has satisfactorily explained 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 cal- 

 cium-poor foods show, naturally enough, defective develop- 

 ment of the bone, but this differs essentially from rickets in that 

 the bone formed is defective chiefly in amount rather than in 

 quality (Stoltzner). Furthermore, such " pseudo-rachitic bone " 

 possesses a marked affinity for calcium salts, and takes them 

 up as soon as they are supplied (Pfaundler). Bland-Sutton, 

 Cheadle, 1 and others consider that a deficiency of fat and pro- 

 teid in the diet is the essential cause. Zweifel and others have 

 advanced the idea that there is a defective absorption of calcium 

 from the foods, depending upon a lack of HC1 in the gastric 

 juice ; this hypothesis seems to be poorly founded. In view 

 of the fact that rickets is not solely a disease of bone tissue, but 

 that all the various important viscera, as well as the muscles and 

 tendons, show pathological changes, it seems most reasonable 

 that rickets should be looked upon as a constitutional disease, in 

 which the bone changes are prominent chiefly because the disease 

 occurs at a time when the bone tissue is most actively forming 

 and when the other organs are relatively quite completely 

 1 Allbutt's System, 1897 (3), 108. 



