WYIISITY 



TISSUES OF THE 



typical gelatine on boiling with water. Otherwise the pathological 

 conditions seem to affect chiefly their quantitative composition, 

 and especially the relationship between the organic and the 

 inorganic substance. In exostosis and osteomalacosis the quantity 

 of organic substance is generally increased. Attempts have been 

 made to produce rachitis in animals by the use of food deficient in 

 lime. From experiments on fully-developed animals contradictory 

 results have been obtained. In young, undeveloped animals ERWIN 

 VOIT produced, by lack of lime-salts, a change similar to rachitis. 

 In full-grown animals the bones were changed after a long time 

 because of the lack of lime-salts in the food, but did not become 

 soft, only thinner, and atrophied. The experiment of removing 

 the lime-salts from the bones by the addition of lactic acid to the 

 food has led to no positive results (HEITZMANN", HEISS, BAGINSKY). 

 A few investigators are of the opinion that in rachitis, as in 

 osteomalacosis, a solution of the lime-salts by means of lactic acid 

 takes place. This was suggested by the fact that 0. WEBER and 

 C. SCHMIDT found lactic acid in the cyst-like, altered bony sub- 

 stance in osteomalacia. 



Well-known investigators have disputed the possibility of the 

 lime-salts being washed from the bones in osteomalacosis by means 

 of lactic acid. They have given special prominence to the fact that 

 the lime-salts held in solution by the lactic acid must be deposited 

 on neutralization of the acid by the alkaline blood. This objection 

 is not very important, as the alkaline stream of blood has the prop- 

 erty to a high degree of holding earthy phosphates in solution, 

 which can be easily proved. 



In rachitis the amount of organic substance has been found to vary between 

 664 and 811 p. m. The quantity of inorganic substance was 189-336 p. in. 

 In opposition to rachitis, osteomalacosis is often characterized by a consider- 

 able amount of fat in the bones, 230-290 p. m. ; but as a rule the composition 

 varies so much that the analyses are of little value. 



The tooth-structure is nearly related, from a chemical stand- 

 point, to the bony structure. 



Of the three chief constituents of the teeth, dentin, enamel, 

 and cement, the last-mentioned, the cement, is to be considered as 

 true bony structure, and as such has been spoken of to a certain 

 extent. Dentin has the same composition as the bony structure, 



