398 BLOOD AND LYMPH. 



hypotonic, and those whose pressure is higher as hypertonic.* 

 The salt that is contained in the plasma in largest amounts is 

 sodium chlorid. In making isotonic solutions this salt is there- 

 fore generally employed. A solution containing nine-tenths of 

 1 per cent, of sodium chlorid (NaCl, 0.9 per cent.) gives the 

 same osmotic pressure as plasma as determined by the effect of 

 each on the lowering of the freezing point (see appendix, Diffusion, 

 Osmosis, and Osmotic Pressure). Such a solution mixed with blood 

 should not and does not alter the water contents of the corpuscles. 

 One may, in fact, use a 0.7 per cent, solution of sodium chlorid with- 

 out causing any noticeable hemolysis/and this strength of solution 

 is generally employed in infusions and experimental work; it con- 

 stitutes what is known in the laboratories as normal saline or physio- 

 logical saline. If, however, one uses a lower concentration some of 

 the corpuscles are hemolyzed, and the number of corpuscles 

 destroyed and the rapidity of the hemolysis increase rapidly with 

 the lowering of the osmotic pressure. While a 0.7 per cent, solution 

 of sodium chlorid suffices in most cases for infusions and for diluting 

 blood, it does not entirely replace the normal plasma or serum, since 

 these liquids, in addition to the sodium salts, contain salts of 

 calcium, potassium, magnesium, etc., each of which has doubtless 

 a certain specific importance. In diluting blood outside the body, 

 when the dilution is large, better results are obtained by using what 

 is known as Ringer's mixture, which consists of the physiological 

 saline solution plus small amounts of potassium and calcium 

 chlorid. One formula for Ringer's solution is: 



Sodium chlorid 0.7 per cent. 



Calcium chlorid 0.026 " " 



Potassium chlorid 0.03 " " 



Hemolysis Caused by the Action of Hdmolysins. It has long been 

 known that the serum of one animal may destroy the red corpuscles 

 of another animal. Thus, rabbits' blood corpuscles added to the 

 clear serum of a dog, cat, or man are quickly destroyed, with the 

 liberation of their hemoglobin. This action was formerly described 

 under the term " globulicidal action of serum," and was compared 

 to the similar destruction, bactericidal action, exhibited by serum 

 toward some bacteria. In more recent literature the term hemol- 

 ysis has replaced that of "globulicidal action," and the hemolytic 

 effect that a serum may exert upon foreign corpuscles is attributed 

 to the presence in it of certain substances which in general are classed 

 as hemolysins. This hemolytic action is not due to a simple differ- 

 ence in osmotic pressure. The serums of the different mammalia 



* For a full consideration of osmotic pressure in its relations to physio- 

 logical processes, see Hamburger, "Osmotischer Druck und lonenlehre. 7 '" 

 Wiesbaden, 1902. 



