REACTION OF THE HOST TO INFECTION 2x5 



or side-chain, rather than in the nucleus. The graphic formula 

 may illustrate this point better. The six carbon atoms in the ring 



H 



I 

 H C O 



\/\ 11 

 C C— C— OH 



I ! 



H— C C 



\/\ 

 C H 



i 

 H 



are stable, and a strong chemical reagent, such as phosphorus pen- 

 tachloride, reacts with the side-chain without attacking the ring. 

 So in the living cell, Ehrich assumes, as a working hypothesis, the 

 existence of a wonderfully complex but coihparatively stable 

 chemical nucleus, with abundant and various more reactive side- 

 chains. These latter serve to combine with food materials in the 

 surrounding lymph, and these are then ultiUzed in the cell by an 

 intramolecular rearrangement of atoms which is always in prog- 

 ress. Useless atomic groups formed in the metabolism of the 

 cell are detached and passed off as excretions. These reactions of 

 intra-molecular rearrangement and molecular disintegration also 

 find their analogues in carbocyclic chemistry. 



Antitoxins.^ — Von Behring and Kitasato (1890-91) showed 

 that animals injected with small non-fatal doses of toxin of the 

 tetanus bacillus, produce as a result of this treatment a some- 

 thing which circulates in solution ii\ the blood plasma, which 

 is capable of neutralizing the poisonous properties of the tetanus 

 toxin. Soon afterward von Behring obtained analogc)us results 

 with the toxin of diphtheria. The protective substances .in the 

 blood were called antitoxins. The exact chemical composition 

 of these substances is unknown. They accompany the pseudo- 

 globulin fraction of the plasma in its chemical analysis,^ but the 



• Banzhaf, Johns Hopkins Hospital Bull., 1911, Vol. XXII, pp. 106-109 



