64 The Feeding of Animals 



of a calf, will, when added to milk at a proper tem- 

 perature, cause the coagulation which gives us the 

 cheese curd.* The probable correct explanation of this 

 familiar phenomenon is that the casein is decomposed 

 into two other substances, one being paracasein and 

 the other an albumin, the first of which subsequently 

 unites with lime salts in the milk and forms the in- 

 soluble substance that we know as curd. The occur- 

 rence of this latter step appears to be proven by the 

 fact that in the absence of lime salts no curd forms, 

 but it immediately appears when such salts are added 

 to the lime -free solution. As milk always contains 

 sufficient lime to make coagulation possible, this ex- 

 planation of the coagulation of casein has chiefly a 

 scientific interest. 



Mention has been made of the clotting of dead 

 muscle, or rigor mortis. As stated, certain investi- 

 gators have suggested that the formation of the muscle 

 clot is a process analogous to the coagulation of blood, 

 and is brought about by ferment action. This view 

 is not yet proven and must at present be considered as 

 only hypothetical. If, however, it is found to be cor- 

 rect, myosin would properly be classed as a derived 

 albuminoid, its progenitor being the native proteid. 



(2) Heat. The effect of a boiling temperature 

 upon the albumins has already been described. They 

 are coagulated into a mass no longer soluble in water 

 and only redissolve by treatment which changes their 

 chemical constitution. The same thing happens to 

 nearly all the globulins, and as with the albumins, 

 this begins at varying temperatures. These coagu- 



*Now held by some that pepsin is the only ferment present and causes 

 these changes. 



