118 COMPOSITION OF BLOOD-CELLS. 



in aspect it is granular. The contents appear to be an albuminous so- 

 lution, in which, fine granules are' suspended. 



Though we have described the mesenteric glands as the original place 

 of formation of the blood-cells, it is to be understood that 

 these become perfected in the circulation of the blood ; and 

 from what will be said respecting the function of the liver, it may be in- 

 ferred that that gland is the seat of a most important change : there 

 probably they receive their iron. That no special organ is exclusively 

 charged with the duty of forming them appears from this, that the first 

 form of blood-cells arises in the germinal area of the embryo when there 

 is, as yet, no gland. 



Composition of Blood-cells. 



Water 688.00 



Haematin (including iron) 16.75 



Globulin and cell membrane 282.22 



Fat 2.31 



Extractive 2.60 



Mineral substances 8.12 



1000.00 



Leaving the water out of consideration, the predominating ingredients 

 of blood-cells are therefore globulin and ha3matin. The former is a sub- 

 stance approaching, in properties, to casein, or perhaps intermediate be- 

 tween casein and albumen. Its constituents, as determined by an ulti- 

 mate analysis, are the same as in the case of those bodies. 



Ha3matin is distinguished by its red color. When isolated, it exhibits 

 Changes of col- the changes of tint characteristic of arterialization in a doubt- 

 or depending f u l manner. There are, however, many facts which lead to 

 t^ C forn?oftne the supposition that the color of arterial and venous blood 

 cells. does no t depend so much on a chemical change in the ha3ma- 



tin as on an alteration of the figure of the discs. 



The constitution of hasmatin is C 44 , H 22 , N 3 , O 6 , Fe. It exists under 

 Properties of two forms, soluble and coagulated. It has hitherto been stud- 

 hrcmatin. } e( j O11 }y i n the latter state, and is soluble in weak alcohol 

 acidulated with sulphuric or hydrochloric acid, but not in water. Its 

 solution is therefore precipitated by the addition of that liquid. In weak 

 solutions of alkalies it readily dissolves. Formerly its characteristic red 

 color was attributed to the iron it contains, but that metal may be en- 

 tirely removed from it without changing its tint. The amount of iron it 

 yields is about seven per cent. 



Ha3matin occurs in the blood-cells associated with globulin, and would 

 seem to owe its origin to the action of the wall of the cell, if it be true 

 that the red cells originate from the white ones. In this formation of 

 ha3matin there are several reasons which lead us to infer that fat takes 

 an essential share. 



