CHEMICAL PHYSIOLOGY. 27 



animals) by the quantity of certain chemical ingredients 

 which are within them. Amongst these latter most 

 notable by its red colour, and in the first place by its 

 chemical constitution, is hematocrystalline.* This sub- 

 stance contains carbon, hydrogen, nitrogen, iron, sul- 



-, -, . .'._._ 



phur, and oxygen, in the proportions indicated by 

 the following formula : C 600 H 960 N 154 FeS 3 177 . This 

 leads to an atomic weight of 13,280, or if it be deter- 

 mined by the quantity of that most stable element, 

 iron, an atomic weight of about 13,000. Persons 

 who have not studied this branch of chemistry, and 

 who perhaps in their handbook, do not read of atomic 

 weights rising above 500, may wonder at the high 

 atomic weight here assigned to hematocrystalline. 

 But this body can now be obtained pure in quantity, 

 and the analyses of crystals have always shown 

 them to contain four tenths per cent, of iron. The 

 crystals are mostly of the rhombohedric system, 

 and appear in tetrahedra, octahedra, with and without 

 prisms, or in prisms only. Their watery properly 

 diluted solution, when examined in the spectroscope, 

 shows two remarkable bands of absorption, and obscu- 

 ration [of the blue and violet end of the spectrum. 

 As the blood of all vertebrate animals, when viewed 



When the blood crystals were first discovered, and their various 

 shapes and properties found out (Funke, Kunde), it was believed and 

 stated (Lehmann) that they consisted of a colourless substance (hema- 

 toglobuline) to which a coloured matter (hematine) adhered like a dye. 

 As long as the researches on this subject moved on the microscopic field 

 only, this idea was plausible ; for many crystals are actually so thin as 

 .to appear colourless under the microscope. But the chemical and 

 spectroscopical researches of the last few years have established the 

 error of this conception and substituted the doctrine of the text. 



