coNCRErioxs 447 



osteoid tissue which prepares it to take the salts out of the bhxxl, 

 and Pfaundler ^- supports this view, suggesting that this prepara- 

 tory change in the osteoid tissue maj' depend upon autolysis, which 

 is perhaps deticient in rickets.'"^ 



On the other hand, after extensive experimental work, Dibbelt '^^ 

 comes to the conclusion that rickets results from excessive elimination 

 of calcium into the intestine, presumably because of the presence of 

 precipitating substances in the intestinal contents, such as P.Og from 

 casein. Agreeing with Dibbelt that the excessive elimination of cal- 

 cium is chiefly through the feces, Schabad '"- after equally extensive 

 investigations, believes that calcium starvation in children, from de- 

 fective absorption, may cause at least a pseudo-rickets, indistinguish- 

 able clinically or chemically from tme rickets. As with osteomalacia, 

 attempts have been made to associate with the etiology of rickets de- 

 fects in the ductless glands, especially the adrenals,^^ thymus,*^^ and 

 parathyroids,^* but as yet without convincing evidence."*'^ 



CONCRETIONS 



All pathological concretions appear to be laid down according to a 

 definite law. There must first be a nucleus of some substance differ- 

 ent from the substance that is to be deposited, and w^hicli is most 

 frequently a mass of desquamated cells, but may consist of clumped 

 bacteria, masses of mucus, precipitated proteins, or a foreign body of 

 almost any sort. Upon this nucleus substances crystallize out of 

 solution, much as cane-sugar crystallizes on a string to form rock 

 -•candy, but with the important exception that among the crystals is 

 usually deposited more or less mucin or other organic substance, 

 M'hicli forms a framework in w^hich the crystals lie, and which re- 

 mains, if the crystals are dissolved out, as a more or less perfect 

 skeleton of the concretion. In no case would the concretion form 

 were it not that the solution is overcharged with some substance, but 

 not infrequently it is the presence of the nucleus that leads to the 

 precipitation of the substance; i. e., the nucleus may play either a 

 primary or a secondary role. AVith few exceptions, the dissolved 

 substance is deposited in crystalline form, although the cn-stalline 

 structure may in time partly disappear through condensation or 

 through filling of the interstices with some other material. Even so 

 structureless a substance as amyloid may, when forming concretions, 

 appear in a crystalline form (Ophiils). The structure of a concre- 



50 See also Nathan. :\red. News, 1004 (84), 391. 



51 Articles in the Arbeiten a. d. Path. Inst. Tiibinofen, Vols, fi and 7; also Verh. 

 Dent. Path. Gesell., 1010 (14), 204; Miinch. med. Woch., 1010 (57), 2121. 



52 Arch. f. Kinderhcilk.. 1000 (52), 47; 1910 (53), 381; 1911 (54), 83; 

 Fortschr. Med., 1010 (28), 1057. 



53 Stoeltzner, Verh. Dent. Path. Ges.. 1009 (13), 20. 

 5-4Erdhcini et al. Frankfurter Zeit. Path., 1911 (7), 178. 



54a Concerning the chemical changes of osteogenesis imperfeeta (congenital fra- 

 gility of bones), see Schabad, Zeit. Kinderheilk., 1914 (11), 230. 



