METHODS OF STUDYING H.EMOLYSINS. 347 



also contains antiamboceptors against the amboceptors of cobra venom. 



IV. The fourth possibility consists in the occupation of the recep- 

 tor by cytophile proamboceptoids, conditions which correspond to 

 those discussed under the simple haemotoxins (page 342). Since the 

 study of amboceptoids is still in its infancy, such cases have not yet 

 been described. Their occurrence, however, is extremely probable 

 and the near future will probably furnish experiences in this direction. 



So far as the details of the experiments are concerned, the previous 

 papers furnish detailed descriptions which may be consulted. The 

 reader is referred to the following: Case I, pages 224-259; II, page 

 209; III, pages 103, 104, 248. 



In any particular instance it is necessary to determine which 

 of these cases obtains. Above all it is necessary to remember that 

 the inhibition need not always be due to a specific binding, but that 

 it may be caused by disturbing factors, which we have classed to- 

 gether under the term antireactive actions. 



For example, if the union of amboceptor and complement does 

 not take place at low temperatures, or if owing to the action of salt 

 the union of complement with the anchored amboceptor, or of ambo- 

 ceptor to the cell receptor, is hindered, these are the result of anti- 

 reactive influences and not of specific inhibitions. As a rule it is easy in 

 any given case to decide which kind of inhibition is present. In most 

 cases the origin and mode of derivation of the substances in question 

 give valuable clues in this direction. If antireactive influences can be 

 excluded, it is not difficult by a logical application of the centrifugal 

 method to classify the case under one of the heads given in the table. 



Naturally these cases may also be combined. Thus, for example, 

 a fluid may contain simultaneously anticomplement, antiamboceptor 

 or anticomplement and procomplementoid. Antiamboceptor and 

 amboceptor, complement and anticomplement in one solution can be 

 excluded, since they mutually neutralize each other. 



Another important point which belongs here is the recognition 

 of concealed amboceptors, whose activatibility is suppressed by the 

 simultaneous presence of anticomplement. For the experimental 

 technique see Morgenroth, page 245. 



It is, of course, impossible to treat exhaustively all the innumer- 

 able variations which come into question. We hope, however, that 

 the methodical exposition here given has shown how the fundamental 

 doctrines of Ehrlich's Side-chain Theory make a systematic study of 

 hsemolysins possible. 



