SPECIAL PROPERTIES OF BLOOD SERUM. 2/9 



Another product of immunization with cells is the agglutinin 

 receptor, while immunization with toxins leads to the forma- 

 tion of receptors of the First Order. Cytotoxins produced by 

 one animal species A, brought into the serum of another ani- 

 mal species B, lead to the formation of anticytotoxins which 

 may be either anti complements or anti amboceptors. 



Toxin molecules on standing or by heating seem to lose 

 some of their activity or toxic power, while their power of 

 combining chemically with or neutralizing antitoxins is not 

 diminished. In this condition they are called by Ehrlich tox- 

 oids, and he explains the behavior by assuming that the toxins 

 have two characteristic groups, one of which, a haptophorous 

 group, persists and combines with the antitoxin while the other 

 is less stable and may be lost; this he calls the toxophorous 

 group. By warming to 55-6o the complement bodies of 

 serum become converted into inactive complementoids, which 

 retain the haptophorous group but lose the zymotoxic group. 

 Amboceptors may lose in the same way one of their combining 

 groups and become amboceptoids. 



It would not be proper in this place to go more fully into 

 the details of the Ehrlich theory; enough has been given to 

 furnish the student an outline of the most important points in 

 the theory. It is of course true that much of the present view 

 is artificial and tentative and, with closer fixation of facts, must 

 be modified. This has been the history of the development of 

 all chemical theories. In its main features the Ehrlich doc- 

 trine gives us a tangible picture of how r the serum may act 

 toward foreign bodies. For the ultimate reasons for the for- 

 mation of immune side chains by stimulation we have no more 

 explanation than we have for many of the manifestations of 

 chemical affinity. In its outlines this theory of the action of 

 immune serum appears wholly fanciful, but in reality it makes 

 no greater claim on the imagination than do some of the old- 

 est accepted theories of general chemistry. 



