1913.] 



Phenomena of" Clot" Formations. 



473 



the presence of milk serum, Witte's peptone, and glycine. But whereas th'e 

 sodium caseinogenate formed precipitates immediately in the cold, which 

 precipitates were not altered in appearance by treatment with alcohol, the 

 calcium salt reacted only on slight warming (the temperature of 25° is 

 sufficient to produce clot formation), and yielded not a precipitate but an 

 aggregation with the characteristic physical appearance and properties of 

 an ordinary milk clot. In both cases rennet could produce aggregation which 

 had been inhibited by the presence of simple adsorbable substances. 



Clot formation could also be produced by the action of strontium and 

 barium chlorides. The former acted quantitatively, like calcium chloride, 

 but the latter had a greater range of action, producing a clot when the 

 calcium caseinogenate solutions were diluted with equal volumes of barium 

 chloride solutions in concentrations varying from N/50 to N/5. Even when 

 the concentration reached N/4 a nearly complete clot was formed. Sodium 

 chloride, when added in concentrations of N/50 to 5N (nearly saturated 

 solution), produced no action. 



Action of Calcium Chloride on Calcium Metacaseinogcnatc. 



A preparation of metacaseinogen was made by warming " natural " 

 caseinogen for two days with water at 37°. The action of calcium chloride 

 solutions on a saturated solution of this preparation in sat. Ca(OH) 2 was 

 investigated. Again an " irregular series " of reactions was produced, but no 

 clots. In the optimal concentrations of calcium chloride only a very partial 

 precipitation was produced, but no precipitate formed (only an opaque fluid) 

 in the presence of excess of this reagent. In these cases, the addition of 

 rennet also produced a precipitate. The general results are indicated in the 

 following table, which illustrates the marked contrast between the behaviour 

 of caseinogen and metacaseinogen : — 





N in 10 c.c. of 

 filtrate. 



Percentage 

 precipitated. 



10 c.c. metacaseinogenate solution — 







+ 10 c.c. N/50 CaClo 



10 -4 







+ 10 c.c. N/25 „ 



5-5 



47-1 





3-5 



66 -3 





3 



71 1 





3-8 



63-4 



+ 10 c.c. N/5 „ 



6-9 



33 -6 



+ 10 c.c. N/4 „ 



10 -4 







+ 10 c.c. N/2 



10-4 







