COMPOUND PROTEINS 151 



"Serum which has been dialyzed against water with very low 

 carbonic acid content until it ceases to give any precipitate, 

 but which can still give with acid a large yield of globulin, is 

 in a most interesting condition. The whole remaining protein 

 is now ionic. It moves towards the anode quite uniformly, 

 therefore it behaves as a whole as the protein ion of an alkali 

 protein compound." 



"Now what does this mean? The presence of other proteins 

 does not interfere with the movement of ionic protein. This 

 point cannot be too much insisted on.* It lies at the root of 

 the evidence. Therefore one starts with protein which behaves 

 uniformly and is electrically inactive, one ends with protein 

 which behaves uniformly and is electrically active, and in the 

 final stage there is no evidence of more than one kind of protein 

 ion. But this residue of uniform character still contains a globulin 

 fraction. It can be split by saturation with a neutral salt or 

 by acidulation into fractions differing in properties according to 

 the mode of separation." 



"When in the cell used for these experiments, which is de- 

 scribed on p. 289, t the upper layer of fluid is a solution of ^^^lyth 

 normal acetic acid and the lower layer is serum and a current 

 is passed for 24 hours, the serum protein becomes slowly charged 

 in such a way that it is repelled from both poles. Therefore 

 in the anodic limb it becomes charged positively, in the cathodic 

 limb negatively. The result of the double repulsion is that the 

 protein is condensed into a hard plate of rubber-like consistency 

 just midway between the electrodes." 



"The phenomena would be explained, on the theory which has 

 been outlined, in this way. In the anodic limb an excess of 

 hydroxyl ions are liberated owing to the electric convection, and 

 these, reacting with the serum protein, convert it into cationic 

 protein. In the cathodic limb the converse reaction with hydrions 

 occurs and is possible owing to the amphoteric nature of proteins. 

 The entire mass of serum protein is thus thrown into the ionic 

 state and in this condition moves with uniform motion, the one 

 half as cationic protein, the other half as anionic protein. The 

 electric current, the most subtle of analyses, detects only one 

 substance, and this substance, owing to its amphoteric nature 

 can exist in either the cationic or the anionic state." 



* Cf. also Chap. XIII. (Author.) f Cf. Hardy's paper. (Author.) 



