PRODUCTION OF ANTIBODIES IQ 



formed that the cell cannot hold them, and they become 

 detached, and float about, ready to unite with any fresh 

 toxin introduced. These free receptor cells constitute 

 the antitoxins, agglutinins, etc. Besides the haptophore 

 group, the toxin molecule contains another group called a 

 toxophore group, which, if it unites with another group 

 on the cell known as the toxophile group, after the union 

 of the haptophore and receptor groups, sets up poisoning. 

 If, however, the toxin come in contact with free receptor 

 cells (antitoxin, etc.), with consequent union of its hapto- 

 phore groups thereto, it cannot produce poisoning, al- 

 though its toxophore groups are free, because the first 

 essential necessary, the fixation of the toxin to the cells by 

 the combination of the haptophore and receptor groups, 

 is no longer possible. The toxophore group is more readily 

 destroyed than the haptophore group. By heating a 

 toxin for some time from 140 to 158 F. its toxicity is 

 destroyed, although it still possesses an affinity for anti- 

 toxin, because the toxophore group, which conditions 

 poisoning, has been destroyed, but the haptophore group, 

 which unites with antitoxin, is intact. 



Production of Antibodies Antitoxin. When an animal 

 is rendered immune to a toxin a substance known as 

 ' antitoxin ' is developed in the blood, which possesses 

 the power of neutralising the toxin. 



Aggressins. Some believe that before infection can 

 take place the bacteria must elaborate additional toxins 

 (aggressins) in the body to overcome the natural resistance. 

 This is presumed to be effected by paralysing the leucocytes 

 and so stopping phagocytosis. Perhaps the aggressins 

 are identical with the true endotoxins of micro-organisms. 



Hcemolysins (see p. 20). 



Cytotoxins. The blood-serum of an animal injected 

 with such cells as leucocytes, spermatozoa, ciliated epi- 

 thelium, or cells from the liver, kidney, or nerves, possesses 

 the power of immobilising and destroying cells of the same 

 origin as those with which the animal was injected. The 

 phenomenon is known as ' cytolysis.' 



Agglutinins. The serum of an animal suffering from, 

 or infected with, typhoid or cholera acquires after a few 

 days the power of causing the aggregation together of 

 typhoid bacilli or cholera vibrios respectively, when these 

 are mixed with it. The agglutination is caused by 



