478 Mr. S. B. Schryver. Investigations on the [Mar. 6, 



is converted into metacaseinogen, which undergoes some further alteration, 

 whereas in the absence of rennet it can form a clot without undergoing this 

 change. The clot produced by the direct action of rennet on milk, which 

 was prepared in the same way as the rennet clot from pure calcium 

 caseinogenate solution, behaved in the same way as the latter, yielding 

 after purification a product of low solubility in lime water. It contained, as 

 the analyses* indicate, products other than those derived from caseinogen, 

 carried down from the milk. The analyses show furthermore that the 

 nitrogen-phosphorus ratios in caseinogen, metacaseinogen (unless heated for 

 too long a period), and in the clots produced both by calcium salts and 

 rennet are the same. There is no evidence, therefore, of any proteoclastic 

 digestion produced by the rennet. The change of caseinogen into meta- 

 caseinogen is not an essential for clot formation, which can, furthermore, be 

 inhibited by the presence of various adsorbable substances. Owing to the 

 lability of caseinogen, especially under the action of rennet, it is not possible 

 to conclude from the experiments on milk-clot formation that the ferment 

 exerts a direct antagonising influence on the substances inhibiting aggrega- 

 tion, although such an action is not by any means improbable. Nor is it 

 possible from the above experiments to directly formulate the chemical 

 changes which take place in clot formation. The evidence points to the fact 

 that it is the free caseinogen which is changed. This substance, as a 

 complex polybasic acid, can conceivably undergo many changes by the 

 simple scission of the elements of water, and although it is not possible to 

 express in the form of an equation the conversion of caseinogen into casein, 

 such a change does not appear to be at all mysterious when considered from 

 a chemical standpoint. 



Summary and Conclusions. 



1. A preliminary account is given of the action of calcium salts on sodium 

 cholate (cholalate). When solutions of these substances are mixed, a clot is 

 formed on heating. Investigations were carried out with the object of 

 determining the relationships between the clotting time and the amounts 

 and characters of the calcium salts. It was found that, in the case of 

 those salts which raise the surface tension of water, the greater the con- 

 centration of the salt the shorter was the time required for clot formation. 

 In the case of salts which lower the surface tension, on the other hand, 

 increase of concentration decreased the clotting time only up to a certain 

 limit of optimal concentration. Above this limit the clotting time was 

 diminished, or the clot formation inhibited entirety. The more a salt 



* These analyses are not published in this communication. 



