464 PKACTICAL PHYSIOLOGY 



developed in the tissue fluids of an animal when the defibrinated blood of an 

 animal of another species is repeatedly inoculated into it. These haemolysins 

 belong to the general group of anti-bodies in which are included the antitoxins, 

 precipitins, agglutinins, bacteriolysins, etc. Haemolysius also sometimes occur 

 as normal constituents of tissue fluids and secretions; for example, they are 

 present in snake venom. 



A particular study of these anti-bodies is more properly a bacteriological than 

 a bio-chemical one, but a study of a few of their essential properties must also be 

 included in the course in bio-chemistry, since many ferments seem to act according 

 to the same laws as those which govern the action of haemolysins. 



Haemolysins. The washed erythrocytes of the rabbit are laked when mixed 

 with the blood serum of the dog or ox. This haemolytic effect of dog's blood 

 serum becomes much more marked, however, if the dog be previously inoculated 

 with defibrinated rabbit's blood. 1 Besides causing haemolysis, the serum usually 

 causes the corpuscles to run together into clumps. This process is called 

 agglutination, and when it occurs in blood the corpuscles settle down and can be 

 filtered off. 



EXPERIMENT VI. (1) Examine microscopically (under cover slip) the effect 

 of dog's serum on rabbit's erythrocytes. (Agglutination, then haemolysis.) 



(2) With a 5 per cent, suspension of washed rabbit's erythrocytes in physiological 

 saline perform the following experiments, ascertaining the degree of haemolysis 

 by allowing the corpuscles to settle, and noting the intensity of colour of the 

 supernatant fluid. Mote also any agglutination. 



In small short test tubes, mix : 



A. 1 c.c. suspension and 0'5 c.c. 0'9% NaCl (control). 



B. 1 c.c. . ,, 0*2 c.c. immunised dog's serum. 



C. 1 c.c. ,, 0*5 c.c. ,, ,, 



Place the tubes in the water-bath at 40 C., and observe after fifteen minutes. 



The haemolysin thus produced by inoculation of foreign blood can be shown to 

 consist of two parts, one of which is destroyed by moderate heat (the thermo- 

 labile body), the other being much more resistant in this particular (the thermo- 

 stable body). The thermo-labile body is not specific in its nature, but is a normal 

 constituent of blood serum; it is usually called the complement or alexine. By 

 specific in this connection is meant that the substance is not confined in its action 

 to one kind of corpuscle. The thermo-stable body is specific in nature, being 

 produced as a result of the inoculation of foreign blood and acting only when 

 brought in contact with blood corpuscles which are of the same kind or are very 

 closely related to those of the blood used for inoculation. On account of analogy 

 between the thermo-stable body and anti-bodies in general it is often called the 

 immune body. 



EXPERIMENT VII. Place 3 c.c. of immunised dog's serum in the water-bath at 

 exactly 50 C. for ten minutes. Allow to cool. Repeat the above experiments, 

 A, B, and C, using the heated serum: no haemolysis will occur, the heating 



1 One intraperitoneal injection of 50 c. c. of rabbit's defibrinated blood will 

 render the dog's serum strongly haemolytic in about four days after the injection. 

 If the injection be repeated once a week for three or four weeks the haemolytic 

 power will be very strong. When an animal is inoculated in this way it is said 

 to be immunised. An equally suitable pair of animals is the rabbit and guinea 

 pig, but the amount of serum obtainable is small. 



