426 BLOOD AND LYMPH. 



and that probably it is this definite substance which is furnished 

 by the blood in activating the venom toxin. 



Speaking in general terms, the serum of any animal is more or 

 less hemolytic in relation to the blood-corpuscles of an animal of 

 another species; but great differences are shown in this respect. 

 The blood-serum of the horse shows but little hemolytic action 

 upon the red corpuscles of the rabbit when compared with the 

 effect of the serum of the dog or cat. Eels' serum has a re- 

 markably strong hemolytic action upon the red corpuscles 

 of most mammals; a very minute quantity of this serum (0.04 

 c.c.) injected into the veins of a rabbit will cause hemolysis 

 of the corpuscles and, as a consequence, the appear- 

 ance of bloody urine (hemoglobinuria). It should be added 

 that this curious toxic or lytic effect of foreign serums is not 

 confined to the red corpuscles. They contain cytotoxins that affect 

 also other tissue elements, especially those of the central nervous 

 system, and may therefore cause death. As little as 0.04 c.c. of 

 eels' serum injected into a small rabbit will cause the death of the 

 animal, the fatal effect being due apparently to an action on the 

 vasomotor and respiratory centers in the medulla. The hemolytic 

 and generally toxic effect of foreign sera has been known for a long 

 time. It was discovered practically in the numerous attempts made 

 in former years to transfuse the blood of one animal into the veins 

 of another. It has been found that this process of transfusion as a 

 means of combatting severe hemorrhage is dangerous unless the 

 blood is taken from an animal of the same or a nearly related 

 species. 



Nature and Amount of Hemoglobin. Hemoglobin is a very 

 complex substance belonging to the group of conjugated proteins. 

 Under the influence of heat, acids, alkalies, etc., it may be broken 

 up, with the formation of a simple protein, globin, belonging to the 

 group of histons (see appendix) and a pigment, hematin. The 

 globin forms, according to different estimates, from 86 to 94 per cent, 

 of the molecule, and the hematin about 4 per cent. Other sub- 

 stances of an undetermined character result from the decomposition.* 

 When the decomposition takes place in the absence of oxygen, the 

 products formed are globin and hemochromogen, instead of globin 

 and hematin. Hemochromogen in the presence of oxygen quickly 

 undergoes oxidation to the more stable hematin. Hoppe-Seyler 

 has shown that hemochromogen possesses the chemical grouping 

 which gives to hemoglobin its power of combining readily with oxy- 

 gen and its distinctive absorption spectrum. On the basis of facts 

 such as these, hemoglobin may be defined as a compound of a protein 

 body with hematin. It seems, then, that, although the hemochro- 

 mogen or hematin portion is the essential constituent, giving to the 



* Schulz, "Zeitschrift f. physiologische Chemie," 24; also Lauraw, ibid., 26. 



