NATIVE AND DERIVED PROTEINS. HARRIS. 79 



the delicate nature of these unions of colloids with metallic ions, 

 unions, which in some cases have been labelled "adsorptions." 

 !N"ow if this sort of thing can go on in non-living albumin what 

 may not be chemically possible in the living bioplasm itself? 

 Dr. Creighton speaks guardedly of "a complex" between the 

 protein and the iron ; but we may at least hold a salt-like union 

 is effected and that the tri-valent iron is chemically bound. In 

 accordance with this we have to remember Professor Macallum's 

 test 1 for inorganic versus bound iron: a dilute (0.5$) solution of 

 pure haemotoxylin gives with inorganic iron a blue black 

 coloration, but with -bound iron no reaction. Under the latter 

 heading come haemogobin and both the potassium ferricyanide 

 and the potassium ferrocyanide. In these the iron atom is 

 bound in some fashion so as not to affect the haemotoxylin in 

 the manner in which it can do when in the unbound condition 

 of inorganic salts presumably ionised. 



It used to be said that inorganic salts given as drugs have 

 a tendency to be deposited in the liver; in more modern 

 terminology it would be said that the hepatic protein has the 

 power of binding the inorganic ions mercury, arsenic, 

 manganese, etc. and therefore retaining them in the liver and 

 so preventing them reaching the circulation in anything like 

 the concentration in which they were absorbed. This capacity 

 of the liver is but one expression of its detoxicating power in 

 virtue of which it fixes many poisons, pathogenic toxins and 

 others, and so prevents their entrance into the circulating 

 blood. 



There must therefore be constant interchanges between 

 the living matter and the inorganic constituents of the 

 lymph, for inorganic salts are being constantly absorbed 

 and constantly execreted and so, on the whole, the per- 

 centage of inorganic constituents in the tissues does not vary. 

 Now the amount of any one constituent iron, calcium, sodium, 



i. Macallum. A. B: J. Physiol., 22, 92, (1897-1898). 



