18 EXPERIMENTAL RESEARCHES 



It is a normal constituent of the blood-serum, 

 and its quantity undergoes no change as a re- 

 sult of the process of immunisation. On the 

 other hand the amboceptor is a new formation 

 brought about by immunisation, and, on the 

 ground of the principle already admitted, it 

 must appear probable that the amboceptor, like 

 the antitoxins, possesses a marked monotropisrn 

 for the corresponding antigen. It was there- 

 fore not the result of accident, but of logical 

 sequence, that my first researches, carried out 

 with Morgenroth, on the mechanism of hasmo- 

 lysis led us to the fundamental conclusion 

 that the amboceptor alone stands in direct 

 relation to the cell, and is quantitatively 

 anchored by it. This anchoring of the ambo- 

 ceptor takes place with a maximum of chemical 

 energy it occurs even at o C. 



The union of the amboceptor and the cell has 

 no harmful results on the latter. On the other 

 hand, the amboceptor-laden cell is exposed to 

 the action of the complement, which by itself is 

 harmless. As regards complements, what I 

 have said about toxins holds true ; they may be 

 regarded as toxin-like substances which possess 

 a haptophoric group, and a toxophoric group 

 which I call the " zymotoxic " group. That 



