1913.] 



Phenomena of " Clot " Formations. 



481 



9. Solutions of calcium metacaseinogenate are, under optimal conditions of 

 concentration, only incompletely precipitated by calcium salts, and do not 

 clot on addition of rennet. 



10. There is evidence that the clot formed on addition of rennet 

 alone is formed from metacaseinogen, as it has a low solubility in half 

 saturated lime water, whereas that formed by addition of calcium chloride 

 alone is formed from caseinogen. Eennet appears also to cause some 

 further change, as up to the present all attempts to reconvert the clot 

 into natural caseinogen (by action of alkalis, etc.) have failed. In this 

 respect, the casein differs from metacaseinogen. Clottable caseinogenate 

 solutions can, however, be readily prepared from clots produced by the action 

 of calcium chloride alone. 



11. It is not possible to formulate accurately the relationships of caseinogen, 

 metacaseinogen, and the clots to one another. Analyses negative the 

 suggestion of anything of the nature of proteoclastic digestion on addition of 

 the rennet. The products are possibly formed from one another by the 

 scission or addition of the elements of water from or to the acid hydroxyl 

 groups, and possibly the various products bear the same relation to one 

 another as do, e.g. the pyro-, ortho-, and metaphosphates. 



12. Although many of the facts appear to support the hypothesis as to 

 ferment actions given above (para. 2), the same cannot be said to be definitely 

 proved by the facts elicited in the study of the phenomenon of milk clotting. 

 The process is rendered more difficult of comprehension by the peculiar 

 instability of caseinogen. There is no doubt, however, that in milk the clot 

 formation depends upon the presence of four series of substances in the 

 system, viz., simple inhibitory substances, colloids, ferment and calcium 

 salt, even if their relative actions cannot be formulated in as simple a manner 

 as that suggested. 



