THE BLOOD AND THE LYMPH 257 



prevents its osmosis out of the capillaries into the tissue-spaces. As 

 Bunge suggests, this large molecule with its relatively great momentum 

 would more easily transport the very heavy atoms of iron than would a 

 small molecule. Its great size and complexity helps undoubtedly in its 

 instability, and this is a very important quality for the performance of 

 its functions. Dry hemoglobin contains nearly 0.5 per cent, of its 

 weight of iron, and it is doubtless on this metal that its quick alternate 

 oxidation and reduction depend. Oxy-hemoglobin is, then, the form 

 of the substance present in the arterial blood and reduced hemoglobin 

 that of venous blood. It is of practical importance that hemoglobin 

 readily forms more or less stable unions with gases other than oxygen, 

 notably carbon dioxide, nitric oxide, and the fatal carbon monoxide. 

 Because of the chemical affinity for the last of these three, coal gas and 

 impure water gas cause many deaths annually, the carbon monoxide 

 replacing and excluding the respiratory oxygen from the erythrocytes. 



Since the development of hematology in the progressive division of 

 medical labor, discussion of the various spectra of the blood, comparison 

 of solutions of hemoglobin, etc., have become less and less a part of the 

 science of physiology proper. Suffice it here to say, then, that each of 

 the different compounds and pigment-derivatives of hemoglobin has an 

 absorption-spectrum peculiar to itself, and that by this means blood 

 may be readily recognized even in very old stains. Much may be learned 

 from the blood by this method and others as to certain pathological 

 conditions. 



THE CHEMICAL COMPONENTS OF THE LEUKOCYTES, or white corpuscles, 

 has so far not been directly determined, except that of pus-cells. These 

 are dead protoplasm, however, whereas the leukocytes are alive, and there 

 is as much difference chemically doubtless as otherwise. Halliburton 

 quotes an analysis of lymphoid tissue made by Wooldridge which the 

 former considers similar to that of leukocytes. This is as follows : 



PROBABLE COMPOSITION OF LEUKOCYTES. 



Water 885.1 



Solids 114.9 



1000.0 



Nuclein 68.78% 



Proteid . . . 1.76 



Histon . . " ... 8.67 



Lecithin 7.51 



Fat 4.02 



Cho'esterin 4.40 



Glycogen 0.80 



Total nitrogen ........... 150.3 



Total phosphorus 30.1 



Among the proteids are alkali-albumin, a myosin-like albumin, para- 

 globulin, and peptone. There is, moreover, probably "thrombin" in 

 small amount. 

 17 



