CALCIUM PHOSPHATE AND CALCIUM CARBONATE. 29I 



solutions the spherules seen were very different in their appear- 

 ances in each set of slides. 



The most noteworthy change was seen where the ammonium salt 

 was used, the deposit being much coarser, with rougher, more 

 irregular surfaces, and as a rule much greater in size and with 

 more tendency toward fusion and toward clumping into masses. 



The whole series for each ion, including those slides with the 

 six accessory agents described above, showed similar tendencies to 

 the plain, unmodified reaction. Each series consisted of 21 slides, 

 consisting of 7 in water, 7 in gelatin, and 7 in albumen. 



Precipitation in Blood Serum. 



Clear serum was pipetted off from test tubes of dog's blood 

 allowed to stand for some hours in a refrigerator. The precipita- 

 tion of calcium phosphate in this serum showed the usual granular 

 amorphous character. Calcium carbonate separated out almost en- 

 tirely in the form of spherules, many of which were quite large. 

 The process of precipitation in blood serum was very complete, 

 covered practically the whole area of the slide, and seemed to be 

 greater than usual in amount. This appearance suggested the 

 thought that the sodium carbonate and phosphate of the blood aided 

 the reaction, making precipitation greater in amount, but further 

 consideration made this seem unlikely, as the usual amount of car- 

 bonate or phosphate was added to the blood, and this alone was 

 sufficient to precipitate more than the total amount of calcium, 

 without the aid of the salts naturally in the blood. 



Mixtures of carbonate and phosphate present the usual char- 

 acter, each salt being precipitated in its own peculiar form and 

 being thus easily identified (Fig. 36). 



Precipitation in Hyaline Cartilage Extract. 

 An extract of fresh hyaline articular cartilage was prepared by 

 mashing it up in distilled water, allowing the mixture to stand a 

 short time, and then filtering it and using the clear solution. The 

 same concentrations of salts were used here as in other cases, but 

 the resulting precipitate was very much less in amount. Precipi- 

 tation occurred only in the area of contact of the solutions, was in 



