CHAPTER XXIV 



THE COLORING MATTER OF THE BLOOD. THE GASES 

 OF THE BLOOD. GAS INTERCHANGE IN THE LUNGS, 

 PHYSIOLOGY OF ALPINISM 



HAEMOGLOBIN 



THE processes of tissue respiration naturally predicate 

 the existence of arrangements which make possible intro- 

 duction of oxygen and elimination of the carbonic acid 

 formed in the combustion changes. These provisions in the 

 warm-blooded animals are, as is well known, provided by 

 the red coloring matter of the blood. In a previous lecture 

 (v. Vol. I of this series, pp. 211-227, Chemistry of the Tis- 

 sues) consideration has been given to the component haema- 

 tin, and its derivatives; attention may therefore here be 

 devoted, from a physiological standpoint, to haemoglobin as 

 a whole. 1 



Production of Hcemoglobin Crystals. Haemoglobin, it is 

 well known, belongs to the group of crystallizable proteins. 

 In many readily crystallizable types of blood one may 

 obtain beautiful haemoglobin crystals by the simple method 

 of Hoppe-Seyler, by laking the blood and placing it in a 

 cold place (perhaps with addition of a little alcohol). Fol- 

 lowing the Hofmeister method of albumin crystallization, 

 F. N. Schulz obtained beautifully formed crystals of haemo- 

 globin by taking a mass of red blood cells, making a laked 

 solution with water, and then adding an equal volume of 

 saturated solution of ammonium sulphate. The precipitate 

 of globulin-like substances is then filtered off and the nitrate 

 allowed to stand. By the process of salting out resulting 

 from the gradual evaporation the haemoglobin separates in 

 the form of crystals. 



Variability of Haemoglobin. The crystals obtained from 



1 Literature upon Haemoglobin: Franz Miiller, Handb. d. Biochem., 1, 662- 

 666, 670-678, 1909; O. Cohnheim, Chemie der Eiweisskorper, 3rd Ed., 1911. 



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