310 PHYSICAL PROPERTIES 



These facts undoubtedly underlie and explain the apparent 

 transformation of serum albumin into serum globulins observed 

 by Moll on heating blood serum to which alkali had been added 

 (57). As Gibson (28) and Schmidt (92) have pointed out, a 

 transformation of serum albumin into globulin would involve a 

 synthesis of glycocoll, which amino-acid is not contained in the 

 albumin molecule. There can be little doubt that the protein 

 which Moll regards as globulin produced from albumin is in 

 reality " denatured" albumin which acidification will flocculate, 

 just as it flocculates a globulin. 



The reversible character of " denaturation " (presumably 

 anhydride-formation without polymerization) is indicated by 

 the observation of Berczeller (2) that while the surface tension 

 of a protein solution which is so salt-free as not to coagulate 

 on heating, nevertheless diminishes on heating, this diminution 

 is reversible and spontaneously disappears on standing. 



It has been shown by Bovie that protein solutions in quartz 

 vessels are coagulated by exposure to ultraviolet light (7). This 

 type of coagulation, like heat-coagulation, demonstrably con- 

 sists of two separate processes. The first process, that of denatu- 

 ration, has, like other photochemical processes, a very low 

 temperature-coefficient and takes place almost as rapidly at 

 C. as at room temperature. The second process, that of 

 agglutination or flocculation, has a high temperature-coefficient 

 indicating that it is not primarily a photochemical process, but 

 a spontaneous consequence of the photochemical denaturation 

 which precedes it. 



Fernan and Pauli (25) have shown that exposure to the radia- 

 tions from radium leads to coagulation of protein (serum albumin) 

 in acid or alkaline solutions. Unlike heat-coagulation the co- 

 agulation in acid solutions by radium radiations is accompanied 

 by no diminution of their H + concentration. 



It has been shown by Bridgman (9) that the application of 

 very great hydrostatic pressures results in the coagulation of 

 white of egg. The pressure is applied very slowly to avoid any 

 rise in temperature due to the compression and that the effect 

 is not due to heat is further demonstrated by the fact that it is 

 more easily elicited at degrees than at 20 degrees. The applica- 

 tion of five thousand atmospheres produces stiffening of the 

 white of egg; six thousand atmospheres compression, applied for 



