CALCIUM PHOSPHATE AND CALCIUM CARBONATE. 303 



And so it might appear that calcium can not be carried in the blood 

 in the form in which it is later deposited in the bone. Pauli and 

 Samec, however, have shown that difficultly soluble salts like cal- 

 cium carbonate may have the amount of their solubility in water 

 increased to over seven-fold in an albuminous solution, and so it is 

 possible that the bone salts, formed by interaction of the blood salts 

 and calcium absorbed into the blood as calcium chloride, might still 

 be carried in solution in the blood and deposited in the bone. 



This is closely related to the views of Barille, whose theory is a 

 step in advance of this, and is strongly supported by such work as 

 that done by Wells. According to this view the calcium is in the 

 blood in the form of a double salt formed here, tribasic calcium 

 carbonophosphate, P 2 O s Ca,H 2 : 2CO s ( CO s H ) 2 Ca. This is soluble 

 in the blood concentration of carbon dioxide. Infiltrating tissues 

 like the bony matrix where the carbon dioxide content is lowered, 

 this is precipitated and immediately breaks up into calcium car- 

 bonate and dicalcium phosphate, which latter salt is converted into 

 calcium phosphate, giving the final proportion found in bone of 15 

 parts calcium carbonate to 85 parts phosphate. Even by this 

 method of precipitation, however, one might expect to be able to 

 see the salts in the matrix, and not being able to do so argues in 

 favor of their being combined with the matrix. The most impor- 

 tant point brought out in this theory is a clear consistent explana- 

 tion supported by experimental evidence, as to the fixed proportion 

 in the amoumt of the two calcium salts, the carbonate and phos- 

 phate, which is always found in their deposition. 



It is interesting to note here the following facts regarding carti- 

 lage. Wells has shown that there is an almost specific power in 

 cartilage for the absorption of calcium salts. My work is in agree- 

 ment with this, for in cartilage extracts there was obtained the 

 least amount of precipitation obtained in any of the experiments, 

 thus showing the power of the substances in cartilage to hold on 

 to the calcium. In spite of this affinity for calcium, however, 

 microscopic evidence of developing ossification in bones preformed 

 in cartilage shows us that the deposition of calcium is never directly 

 in a cartilaginous matrix, but that the cartilage preceding the bone 

 is destroyed and replaced by the organic bony matrix which is of 



