84 HAND-BOOK OF PHYSIOLOGY. 



The properties of hsemoglobin will be considered in relation to the 

 Gases of the blood. 



Chemical Composition of the Colorless Corpuscles. In conse- 

 quence of the difficulty of obtaining colorless corpuscles in sufficient num- 

 ber to make an analysis, little is accurately known of their chemical com- 

 position; in all probability, however, the stroma of the corpuscles is made 

 up of proteid matter, and the nucleus of nuclein, a nitrogenous phos- 

 phorus-containing body akin to mucin, capable of resisting the action of 

 the gastric juice. The proteid matter (globulin) is soluble in a ten per 

 cent, solution of sodium chloride, and the solution is precipitated on the 

 addition of water, by heat and by the mineral acids. The stroma con- 

 tains fatty granules, and in it also the presence of glycogen has been 

 demonstrated. The salts of the corpuscles are chiefly potassium, and 

 of these the phosphate is in greatest amount. 



Chemical Composition of the Plasma or Liquor Sanguinis. 

 The liquid part of the blood, the plasma or liquor sanguinis in which the 

 corpuscles float, may be obtained in the ways mentioned under the head 

 of the Coagulation of the Blood. In it are the fibrin factors, inasmuch 

 as when exposed to the ordinary temperature of the air it undergoes coag- 

 ulation and splits "up into fibrin and serum. It differs from the serum 

 in containing fibrinogen, but in appearance and in reaction it closely 

 resembles that fluid; its alkalinity, however, is less than that of the 

 serum obtained from it. It may be freed from white corpuscles by filtra- 

 tion at a temperature below 41 F. (5C.) 



Fibrin. The part played by fibrin in the formation of a clot has 

 been already described (p. 66), and it is only necessary to consider here 

 its general properties. It is a stringy elastic substance belonging to the 

 proteid class of bodies. It is insoluble in water and in weak saline solu- 

 tions, it swells up into a transparent jelly when placed in dilute-hydro- 

 chloric acid, but does not dissolve, but in strong acid it dissolves, pro- 

 ducing acid-albumin; 1 it is also soluble on boiling in strong saline solu- 

 tions. Blood contains only -2 per cent, of fibrin. It can be converted 

 by the gastric or pancreatic juice into peptone. It possesses the power 

 of liberating the oxygen from solutions of hyclric peroxide H a O a . This 

 may be shown by dipping a few shreds of fibrin in tincture of guaiacum 

 and then immersing them in a solution of hyclric peroxide. The fibrin 

 becomes of a bluish color, from its having liberated from the solution 

 oxygen, which oxidizes the resin of guaiacum contained in the tincture 

 and thus produces the coloration. 



1 The use of the two words albumen and albumin may need explanation. The 

 former is the generic, word which may include several albuminous or proteid bodies, 

 e.g., albumen of blood; the latter, which requires to be qualified by another word, is 

 the specific form, and is applied to varieties, e.g., egg-albumin, serum-albumin. 



