the chemistry of the benzol group), by means of which the cell enters into 

 chemical relation with food and other substances brought to it by the circu- 

 lation. These receptors are exceedingly numerous, as the nutritive sub- 

 stances upon which the cell depends for its maintenance are very varied. 

 Besides these general receptors the special cells also have different and 

 special side chains; then, too, there exist very great quantitative differ- 

 ences among the latter; and finally it must be added that the selective 

 activity of the cells depends upon the variability of these receptors. 



When an infection occurs, pathological material is brought to the cell 

 bodies instead of physiological normal substances. Certain of these poi- 

 sonous products find suitable receptors in all of the cell groups, others fit 

 only into distinct groups of cells, while a third class are not taken up at all. 

 The organism which possesses no receptors for any of the pathological 

 agents cannot assimilate any deleterious substances and is therefore im- 

 mune. Lack of amboceptors is therefore a natural form of immunity. 

 The organism, having only a special group of cells for the reception of cer- 

 tain pathological matter, will make use of these cells for the binding and 

 assimilation of the toxic material. For example, the nerve cells alone have 

 receptors for tetanospasmin ; no matter how or when the poison is intro- 

 duced into the organism the nerve cells will absorb it. As this toxin is 

 poisonous for the central atom group (Leistungskern) of the nerve cell, the 

 latter is destroyed. The union between the nerve cell receptors and the 

 tetanospasmin toxin is only the preliminary act for the cell destruction; 

 the actual death of the cell being caused by the action of the toxophore 

 group of the poison upon the functional radicle of the cell. If, however, 

 such receptive side chains are possessed not only by the brain but also by 

 other cells, e.g., connective-tissue cells, the tetanospasmin will in part be 

 bound by the latter. The toxophore group of the toxin does not have 

 any harmful effect upon the functional radicle of these cells, and thus no 

 toxic effects will be incurred by the union, and the nerve cells remain 

 unaffected. 



The number of receptors which cells possess for tetanospasmin, for 

 example, are limited and after their junction with the tetanospasmin, are 

 rendered useless and inactive. By the normal repa.rat.ive mechanism of 

 the body, new receptors are generated. This reparative process does not 

 as a rule stop at a simple replacement of lost elements, but according to 

 the hypothesis of Weigert tends to overcompensation. The receptors 

 eliminated by toxin absorption are reproduced in an excess of the simple 

 physiological needs of the cell. Continuous and increasing dosage of the 

 toxin soon leads to such excessive production of receptors that the latter 

 find no more room to be attached to the cell, but are cast off and circulate 

 free in the blood. They still, however, retain their property of being able 

 to combine with tetanospasmin. 



