ANTI-H^EMOLYSINS 451 



differently towards different reagents. By treating goat's serum with, 

 four different reagents (digestion with papain, action of alkali, 

 heating to 50 C., and uniting with various erythrocytes) Ehrlich. 

 and Sachs were able to separate four varieties of complement. 



This fact concerning the complex nature of the complement has 

 also a clinical bearing. Certain diseases (cholera and typhoid) are 

 produced by bacterial growth in the tissues (in contrast to diphtheria 

 and tetanus, which are due to bacterial poisons or toxins). These 

 bacteria may be killed by injecting anti-bactericidal serum into the 

 patient. This is obtained from an animal into which cultures of 

 the bacillus in question have been inoculated in gradually increasing 

 dosage. Now, such inoculations will only increase the amboceptors ; 

 they will not affect the complement. The immune (i.e. anti- 

 bactericidal) serum will, therefore, contain plenty of amboceptors, 

 but the complement present may not be of sufficient variety 

 to react with these. This complement will, moreover, gradu- 

 ally diminish in amount if the anti-bactericidal serum be kept 

 some time. Wasserman ( 7 ) has, therefore, suggested that fresh 

 normal serum should be injected into the patient along with the 

 bactericidal serum. Experimenting on animals, he found that this 

 very materially assisted the action of the bactericidal serum. 

 When applied to clinical therapeutics, however, the large amount 

 of serum necessary seems to have an unfavourable action, and the 

 method has not been fully elaborated. 



It will be gathered from what we have learned about hsemo- 

 lysins so far, that they are, in all their reactions, exactly like 

 toxins. We have also seen that by the gradual inoculation of 

 toxins into an animal, antitoxins are produced ; and, if our 

 analogy is to hold, we must expect that hsemolysins will similarly 

 produce anti-hsemolysins. What evidence have we then of this ? 



ANTI-H^:MOLYSINS 



As we shall see later, the serum of an eel's blood can produce very 

 active haemolysis when mixed with the erythrocytes of most other 

 animals. This is because it contains a hsemolysin. If, now, the 

 eel's serum be injected intravenously into a susceptible animal, in 

 small non- lethal doses at first, and the injection repeated in 

 increasing dosage, the blood serum of the latter will, after a few 

 weeks, become endowed with the property of inhibiting this 



