AMBOCEPTORS AND COMPLEMENTS 339 



and complement, and that the latter then causes the lysis or solution of 

 the antigen. The connecting link or antibody of this nature is known 

 as an antibody or receptor of the third order. 



Different cells produce their own and specific interbodies or ambo- 

 ceptors. Thus bacteria or vegetable cells, blood-corpuscles, and va- 

 rious other cells, such as ciliated epithelium, spermatozoa, renal epi- 

 thelium, etc., when present in the form of an infection or when injected 

 into an animal, generate different and specific amboceptors, which bring 

 about their solution by binding them with a ferment or complement. 

 One ferment or complement does not serve for all; there are various 

 ferments, which act with the different amboceptors, but all have proper- 

 ties so nearly alike that many believe, with Bordet, that but a single 

 complement exists. 



Definition. This special digestive and lytic process is known to 

 occur with cells, and hence the antibodies capable of bringing about this 

 action are called cytolysins, or substances that cause lysis or solution of 

 the various cells that may be their antigens. 



It is well to remember that, according to Ehrlich, the three orders of 

 antibodies each have their counterpart, both in structure and in effect, 

 in the receptors serving for the normal nutrition of cells. For the sim- 

 plest molecule of food that is in solution the cell is provided with a simple 

 receptor for union with the molecule, which is then directly assimilated. 

 This receptor is similar to an antitoxin, or an antibody of the first order, 

 which destroys its toxin directly and without further ado. More 

 complex food material must first undergo some preparation by the cell 

 before it can be assimilated, and accordingly we find receptors provided 

 with a more complex structure which have their counterpart in the anti- 

 bodies of the second order, or those possessing a special toxic portion 

 that agglutinates or precipitates their antigen or prepares it for phagocy- 

 tosis. It is possible that with physiologic substances this is all that the 

 cell requires of its receptor, but so far as is known, it would appear that 

 for antibodies this action does not in itself injure the antigen, but is 

 rather one step toward preparation for its further destruction. Or- 

 ganized and complex food substances must be digested before assimila- 

 tion can occur, and here we find that the receptor acts as a link in binding 

 the food molecule to a ferment, with resulting dissolution and assimila- 

 tion of the products of solution. These are called receptors of the third 

 order, and have their counterpart in similar antibodies, the cytoly- 

 sins, which act as links or interbodies between antigen and a comple- 

 ment, the latter being entirely free and separate, and independent of 

 the receptor or antibody (interbody) itself (Fig. 95). 



