ALBUMINOUS BODIES. 67 



into a globulin and a coloring matter, hcematin, containing iron. 

 It differs from all other bodies of a similarly complex nature from 

 the fact that it readily crystallizes, and also in the very remark- 

 able manner in which it combines with oxygen, and again yields 

 it up. 



Group II. ALBUMINOUS BODIES. 



It is difficult to say how far these bodies exist as such in the 

 living organism, but they can be obtained from nearly all parts, 

 particularly those which contain active protoplasm, and after its 

 death they can be detected in abundance. As may be seen, by 

 testing for their presence in living protoplasm, the addition of 

 any chemical reagent or treatment causes its death, so that, 

 although albumins appear in the test tube, this cannot be 

 accepted as proof that they would have answered to the tests 

 before the protoplasm was changed by its death. 



They do not occur normally in any secretion except those sub- 

 stances which tend to nourish the adult body, and to form and 

 nourish the offspring, viz., the ovum, semen and milk. No satis- 

 factory formula has been suggested to express their chemical 

 composition, but the average percentage of the elements they 

 contain is remarkably alike in all members of the group. This 

 may said to be in round numbers as follows : 



Oxygen, 21 per cent. 



Hydrogen, 7 " 



Nitrogen, 16 " 



Carbon, 53 '* 



Sulphur, 1 



They are amorphous, of varying solubility, and with one 

 exception indiffusible in water. 



As far as we know at present, albumins cannot be constructed 

 de novo in the animal body, but must be supplied in one form or 

 another as part of the food. Albumins are therefore always the 

 outcome of the activity of vegetable life. 



They can be recognized by the following tests : 



1. Strong nitric acid gives a pale yellow color to strong solu- 

 tions or solid albumin, which turns to deep orange when 

 ammonia is added (Xanthoproteic test). 



