COLLECTED STUDIES IN IMMUNITY. 



inactivating and adding complement without finding that the con- 

 stantly increasing amount of complementoid hindered- the action 

 of the complement. This phenomenon can be explained only by 

 assuming that in the change to complementoid, the haptophore group 

 of the complement suffers a diminution of its affinity for the comple- 

 mentophile group of the immune body. 



In the toxoids of diphtheria poisons the circumstances are some- 

 what different, for Ehrlich found that in the hemitoxin zone of the 

 poison spectrum the affinity suffers no change through the forma- 

 tion of toxoid. On the other hand, M. Neisser and Wechsberg in 

 another case, namely that of staphylotoxin, have been able to demon- 

 strate a decrease in affinity occurring with the change into toxoid. 

 This behavior is analogous to that of the complementoids observed 

 by us. Hence no general rules governing the affinities in toxoid 

 and complementoid formation can be laid down; the circumstances 

 must be investigated separately in each case. From what slight 

 differences in the constitution of the molecule enormous differences 

 in affinity may arise is seen by studying certain organic acids. Thus, 

 for example, a and /? resorcylic acids differ from each other merely in 

 the position of the two hydroxyl groups; the constants of their 

 affinities, however, differ from each other by over a hundred times. 

 We may therefore perhaps assume that in our special case it depends 

 on the relative positions of the haptophore and hoxophore group 

 and the corresponding relations thereby determined whether any 

 change in one group can retroactively affect the other. 



III. Concerning Autoanticomplements. 



In the third communication, on isolysins, we pointed out that 

 the organism possesses certain contrivances by means of which 

 the immunity reaction, so easily produced by all kinds of cells, is 

 prevented from acting against the organism's own elements and 

 so give rise to autotoxins. Further investigations made by us have 

 confirmed this view, so that one might be justified in speaking of 

 a "horror autotoxicus" of the organism. These contrivances are 

 naturally of the highest importance for the existence of the indi- 

 vidual. During the individual's life, even under physiological though 

 especially under pathological conditions, the absorption of all material 

 of its own body can and must occur very frequently. The formation 

 of tissue autotoxins would therefore constitute a danger threatening 

 the organism more frequently and much more severely than all 



