COMPOUND PROTEINS 153 



H H 



I I 



2HOOC.Ri.N" + 2-H-NaOC.Ri.NH2 + HOOC.R.N" + 

 I I 



OH OH 



RLCOOH 



I 



H N = NaOC.R!.NH 2 



++NaOC.R.NH 2 = HOOC.R.N ( ) NaOC.R.NH 2 + 2 H 2 O 



I \/ 



OH N = NaOCRi.NH 2 

 I 

 Rx.COOH 



Hydrolytic dissociation of this complex, just as in the case of the 

 salt-alkali-protein compounds described in the previous chapter, 

 would result in its decomposition, partial or complete, and hence, 

 if the complex were non-ionic (and, as we have seen, the homol- 

 ogous compounds with inorganic salts are non-ionic) mere dilu- 

 tion of its solution or the removal of dehydrating agents (salts) 

 might result, as in Hardy's experiments, in the splitting off of 

 fraction after fraction of ionic protein. A very faintly alkaline 

 reaction would probably favor its stability, a mere trace of acid 

 might be expected to disrupt the complex (Cf. equation iv, Chap. 

 VI).* It will be found, I believe, that the presence of such 

 protein-complexes as these, in the tissues and tissue-fluids, affords 



* The fact that this complex will pass through the pores of a porcelain 

 filter, while the simpler, ionic protein will not, is due to its non-ionic character. 

 The thesis will be developed in a later chapter (Chap. XI), upon a very 

 extensive experimental basis, that the colloidal, non-filterable, viscous character 

 of solutions of ionic protein is attributable not to the size of the protein particles 

 but to the size of the associated complex of water molecules, which is much larger 

 in solutions of ionic than in solutions of non-ionic protein. The non-filterable 

 character of ionic globulin is to be interpreted in the same way as the non- 

 permeability of a porous pot for mixtures of propyl alcohol and water, although 

 it is permeable to both water and propyl alcohol when they are pure (S. U. 

 Pickering (94)). Just as, in Pickering's experiment, propyl alcohol, when dis- 

 solved in water, will not pass out through the walls of a porous pot into the 

 surrounding water, not because the wall of the pot is impermeable to propyl 

 alcohol, for pure propyl alcohol will pass through the pot, but because it is 

 impermeable to the molecule of propyl alcohol plus its associated complex of 

 water molecules, so ionic globulin will not pass through porcelain because the 

 porcelain is impermeable to the globulin ion plus its associated complex of 

 water molecules. 



