1913] Charles Frederick Bolduan 253 



Anti-antibodies. But even this list does not exhaust the list 

 of "antibodies" which it is possible to produce. When enzymes 

 are injected into an animal, the latter responds by producing anti- 

 enzymes, and when certain " antibodies " are injected, anti-anti- 

 bodies are produced. 



Immunity regarded from the Standpoint o£ cell nutrition. 

 The whole subject of infection and immunity, and particularly the 

 production of the antibodies just discussed, is best appreciated when 

 regarded from the Standpoint of nutrition; for what, after all, is 

 this apparent conflict between bacteria and the animal body but 

 the mutual attempt of each to use the other for food. Let it be 

 noted that production of the various antibodies takes place only 

 when the bacteria or other allen cells are introduced parenterally, 

 i. e., by ways other than the gastrointestinal tract. We may ex- 

 plain this by saying that when introduced by the gastrointestinal tract 

 the molecules of the food stufifs (organic) are split up and rebuilt 

 in such a way that the material requires no further extensive altera- 

 tion in order to serve as food for the various cells of the body. In 

 the animal body this breaking down and building up is delegated to 

 certain specialized cells ; in the primitive organisms, however, we 

 must believe that each cell was required to break down and build up 

 its own food. When parenterally situated cells of the higher animal 

 are thus presented with the unprepared food which the parenteral 

 introduction brings them, it may be assumed that they behave as 

 does the primitive cell, and proceed to lay hold of and attempt to 

 assimilate the injected material. With this introduction, we may 

 pass at once to a consideration of Ehrlich's "side chain theory," 

 which still offers the best explanation for the formation of the 

 various antibodies. It is essentially a theory of cell nutrition. 



Ehrliches "side chain" theory. According to Ehrlich's 

 conception, every cell is armed with a large number of chemical 

 groups whose function is to lay hold of nutriment and anchor this 

 in the cell. These groups he calls receptors or side chains. Only 

 such substances can serve as nutriment which can thus be bound 

 chemically to the cell protoplasm. He believes that the receptors are 

 of at least three different kinds, and speaks of receptors of the " first 

 Order," "second order" and " third order." These are best de- 

 scribed with the aid of a diagram such as the accompanying one. 



