126 Becof/nifion of the Imlivkhial hji Haemoh/h'c Methods 



removed from the serum, which is now found to be without any trace 

 of solvent action on fresh corpuscles. 



The serum of the rabbit which has been injected with ox corpuscles 

 resembles the precipitin sera referred to above in that it is not strictly 

 specific, but in addition to haemolysins for the ox, also contains 

 haemolysins for animals of species allied to the ox, such as the sheep, 

 goat etc. 



If it is desired to remove these secondary haemolysins, this is easily 

 accomplished by the method of " exhaustion " or " elective absorption." 

 Supposing, for instance, we wish to remove the haemolysin for the 

 sheep, it is only necessary to " exhaust " the serum with sheep's 

 corpuscles, i.e. to leave it in contact with sheep's corpuscles at 0° C. 

 and then remove these corpuscles by centrifuging. The serum is then 

 found to be quite without action on sheep's corpuscles, whilst it remains 

 still active for the corpuscles of the ox. In this way sera, which are 

 originally haemolytic for two or three species, can be artificially 

 rendered haemolytic for only one of them, that is to say they can be 

 made more specific. 



Bordet having shown that the injection of blood corpuscles into 

 an animal of a different species gave rise to a haemolysin, Ehrlich and 

 Morgenroth investigated the results of injectiiig animals with the 

 corpuscles of other animals of the same species and found that in 

 this case also as a rule a haemoly.sin is formed. Thej' injected a 

 goat with blood obtained from another individual of the same species 

 and found that the serum of an animal so treated became haemolytic 

 for the corpuscles of the individual whose blood was injected, and also 

 for those of other goats but never for its own corpuscles. (To use their 

 nomenclature : it became isolytic but not autolytic.) 



By injecting goats with goat's corpuscles, thirteen of these isolytic 

 sera were prepared and a careful study of their properties, by methods 

 too complicated to be gone into here, revealed the fact that they 

 all differed fi-om one another, i.e. that they represented different 

 isolysins. 



The investigation of the isolysins was continued by Todd and 

 White"'' '='■ '^' who had at their disposal 106 cattle which in the course 

 of their immunisation with cattle plague had been injected with large 

 quantities of the blood of other cattle. 



An examination of the sera of these animals showed that 

 76 of them were very highly haemolytic for the corjDuscles of normal 

 cattle and a detailed investigation gave most interesting results. 



