288 JAMES CRAWFORD WATT. 



ring in its usual amorphous form, the carbonate in typical crystals 

 and spherules. Similar conditions were found by Rainey in gum 

 arabic. 



The colloids gelatin and albumen were chosen as being artificial 

 media easily prepared which might be looked on as approximately 

 comparable respectively to the bony matrix and to the blood serum 

 or to cellular tissues. Reactions in gelatin might give a clue to 

 those "in bone, and similarly reactions in albumen might indicate 

 processes of calcification in other tissues. After studying the re- 

 actions in these simple media, they were further modified by the 

 addition of various substances which are either normally or patho- 

 logically found in the blood or tissues, to see what effect these 

 special substances would exert. 



Further experiments were also carried out to study the effect of 

 the hydrogen-ion concentration of the colloid. To complete this 

 stage of the work reactions were followed in cartilage extract and 

 in blood serum. Then specimens of bone from various animals 

 were examined to see if there was any correlation between the 

 structure of their matrix and the results obtained experimentally 

 in the various media. 



The Influence of Other Agents on the Precipitate. 



The substance whose influence was to be investigated was added 

 in equal concentration both to the sodium carbonate or phosphate, 

 and to the calcium chloride solutions which were to react to form 

 the precipitate. The new agent was thus balanced so that its action 

 could not be one sided. 



The agents used and their concentration in solution were : 



M/io sodium chloride, same proportion as in human blood serum, 

 o.i per cent, dextrose, same proportion as in human blood serum 



(Gradwohl). 

 0.05 per cent, urea, same proportion as in human blood serum. 

 0.1 per cent, lecithin. Blood serum contains 0.7 per cent. (Wells). 

 1.0 per cent, acetone. Simulating conditions in acidosis. 

 0.5 per cent, ethyl alcohol. 



The effects produced on the precipitation of calcium carbonate 

 were quite definite for some of these substances, and in some in- 



