8 Veterinary Medicine. 



for a greater or less length of time and thus establishes an ac- 

 quired immunity. 



It must be assumed that these receptor^, before their detach- 

 ment from the cell have acquired the special affinity which makes 

 them available for engaging with the haptophores and toxins of 

 the invading disease, and of that only, as the acquired immunity 

 is from the one affection only. 



Isolysins or Autolysins (isos, similar, autos, one's self) are 

 solvents of the red globules produced by injecting excess of the 

 blood of the same species of animal. They do not act the same 

 on the blood of all animals of the same species, showing a differ- 

 ence in the globules in animals of the same species. This sug- 

 gests a reason why different individuals are not all equally sus- 

 ceptible to the same microbe, and why the action of antitoxins 

 should be more effective in one animal than another of the same 

 breed. 



Agglutinins : Hemagglutinins. These are elements in the 

 normal and diseased blood-serum, which cause clumping in masses 

 of the blood globules of another animal, or of bacteria. The action 

 bears an apparent relation to that of hemolysis and the two con- 

 ditions usually coexist. Normal goat serum agglutinates the red 

 corpuscles of man, pigeon and rabbit : normal rabbit serum ag- 

 glutinates typhoid and cholera bacilli. The serum of a person 

 with a well developed case of typhoid fever clumps the bacilli in 

 an artificial culture of the typhoid germ. The same holds with 

 the blood serum of hog cholera, and the hog cholera bacillus. In 

 these cases and in others this is made a mode of diagnosis. The 

 union of the agglutinin and the bacillus is shown by the follow- 

 ing : To a serum which agglutinates both typhoid and cholera 

 bacilli, some typhoid bacilli are added and the whole centrifuged 

 when the clear fluid will no longer clump the typhoid. bacilli, but 

 still clumps the cholera ones. Conversely if the cholera bacilli 

 are first added and the whole centrifuged the clear fluid no longer 

 acts on the cholera bacilli, but will still act on the typhoid. The 

 agglutinins of the bacilli introduced adhere to the surface of 

 these bacilli and are precipitated with them, while those that 

 would clump the bacilli of the other disease remain in the clear 

 liquid. The same applies to the agglutinins in their action on 

 blood cells. To a normal goat serum, which agglutinates the 



