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



Other Methods of Obtaining Clots. The General Character of Clot Formation. 



The experiments already quoted seem at first sight to fully confirm the 

 theory as to the general action of ferments and inhibitory substances 

 indicated in the introduction. They do not, however, indicate the actual 

 chemical process of clot formation, and the whole subject is somewhat com- 

 plicated by the fact that caseinogen itself is very labile. Further investiga- 

 tions were therefore necessary to ascertain the nature of the chemical 

 processes involved in clot formation, and to determine whether the change of 

 caseinogen was a necessary preliminary, and whether calcium or any other 

 alkaline earth was an essential constituent of the clot-producing system. 



During the course of these additional researches, it was found that it was 

 possible to produce a clot by other methods. 



It was found that the calcium caseinogenate solution alone, and without 

 the addition of another calcium salt, could produce a clot on the addition of 

 rennet. This clot formation, which can take place at room temperature, was, 

 however, completely inhibited when the caseinogenate solution was diluted 

 with a equal volume of milk serum, i.e. when the milk serum constituents 

 were in only half the concentration in which they exist in milk. In the 

 presence of such quantities of inhibitory solutions, the presence of an 

 additional calcium salt is necessary to produce a clot. As caseinogen can be 

 converted into nietacaseinogen by water, it is conceivable that a similar 

 reaction would take place more readily in the presence of rennet. Iu this 

 case calcium caseinogenate should form a mixture of free nietacaseinogen and 

 calcium metacaseinogenate and there would then exist in the system more 

 nietacaseinogen than is necessary to saturate all the calcium present, for, as 

 has already been shown above, a saturated solution of this substance in 

 \ sat. Ca(OH) 2 contains only about a third of the amount of nitrogen contained 

 in a corresponding solution of caseinogen. As a matter of fact there is 

 evidence, which is given in greater detail below, that the clot formed in the 

 presence of rennet is produced from metacaseinogen. It is conceivable, 

 therefore, that the clots are formed from the free caseinogen or meta- 

 caseinogen directly and not from the calcium salts. 



This supposition is also confirmed by other facts. By reference to the 

 table given on p. 464 it will be seen that \ saturated lime water dissolves 

 less than half the amount of caseinogen or metacaseinogen dissolved by 

 half-saturated lime water, whereas completely saturated lime water dissolves 

 only very little more than double the amount dissolved by the 

 \ sat. Ca(OH) 2 . Eepeated experiments on the solubility of natural caseinogen 

 in \ sat. Ca(OH) 2 gave solubility numbers varying between 8 and 11 instead 



