TOXINS 



139 



microbic serum, and the immunity, antimicrobic passive immunity. Some immune 

 sera are both antitoxic and antimicrobic. 



It is well to remember that some organisms produce a toxin which is given off 

 while the bacterium is alive; and in other instances the toxin is intracellular and is 

 only given off when the bacterium disintegrates; consequently, an antimicrobic 

 serum may cause the liberation of toxin. Diphtheria, tetanus, or botulism antisera 

 are instances of antitoxic sera, while practically all others are antimicrobic. There 

 is but one factor to consider in an antitoxic serum and that is the protoplasmic 

 particles which are thrown off from the cell in response to the injury incident to 

 the attack upon the cell by the 

 toxin particles. This free particle 

 in the circulation represents the 

 entire mechanism of antitoxic- 

 immunity. It is capable of unit- 

 ing with the toxin molecule and 

 neutralizing its toxic power, or 

 rather so binding its combining 

 end (haptophore group) that it is 

 incapable of attaching itself to a 

 cell, so that the poisonous end of 

 the toxin (toxophore group) can- 

 not have access to the cell. 



The term toxin, strictly 

 speaking, is applicable only 

 to such bacterial poisons as 

 (i) require a period of in- 

 cubation before being capa- 

 ble of manifesting toxic 

 symptoms and (2) can pro- 

 duce antitoxins. 



FIG. 45. Receptors of the second order 

 and of some substance uniting with one of them. 

 Journal of the American Medical Association, 

 1905, p. 1113.) c, Cell receptor of the second 

 order; d, toxophore or zymophore group of 

 the receptor; e, haptophore of the receptor; /, 

 food substance or product of bacterial disin- 

 tegration uniting with the haptophore of the 

 cell receptor. 



(For further discussion of toxins 

 and antitoxins see under diphthe- 

 ria, tetanus, botulism, and pyocy- 



aneus infections.) In antimicrobic sera we have two factors to consider, the 

 first is a protoplasmic particle quite similar to the antitoxin molecule, but which 

 in itself has no power of injuring its specific bacterium. This particle is gen- 

 erally referred to as the amboceptor or immune body. It is the specific product of 

 the activity of a specific bacterium or foreign cell against the body cells attacked. 

 It withstands a temperature above 56 C. and of itself is incapable of injuring the 

 bacterium in response to whose attack it was produced. The second factor in the 

 bacteriolysis of the specific bacterium, or the haemolysis of the specific foreign cell, 

 is something normally present in the serum of every animal, and which is capable 

 of disintegrating a foreign cell or bacterium, provided it can have access to the cell 

 or bacterium through an intermediary amboceptor (hence the amboceptor is some- 



