662 PHYSIOLOGICAL CHEMISTRY. 



rence of the interaction of the amboceptor and antigen, while its ab- 

 sence is shown by the failure of the reaction. The reagents com- 

 monly used are red blood-corpuscles and the corresponding haemolysin 

 (amboceptor), since the interaction is shown by a visible change, 

 haemolysis, and if no reaction occurs the mixture remains unchanged. 



This procedure is used in the Wassermann reaction for syphilis. 

 If a mixture be made of the blood-serum of a syphilitic patient, an 

 emulsion of animal lipoids, and complement, it is found that the com- 

 plement becomes absorbed or fixed, so that if the mixture be tested 

 for complement by the addition of red blood-corpuscles and the cor- 

 responding haemolysin, no haemolysis will occur. If, on the other 

 hand, the patient has not syphilis, no fixation of complement will 

 occur, the complement will be left free to act, and will produce hae- 

 molysis when the corpuscles and haemolysin are added. 



Ehrlich, in explaining his theory of immunity, begins by describ- 

 ing the cell as consisting of a certain group of atoms forming an 

 essential nucleus which is combined with several different groups of 

 atoms, called side-chains, varying in composition and structure. 



Each of these side-chains has atoms arranged in such a way that 

 they present affinities for combining with groups of atoms of nutrient 

 or other material circulating in the animal fluids. These groups he 

 calls receptors, and the arrangement of atoms, by virtue of which 

 combination occurs, a haptophore group. 



Thus, specific lysis is due to the action of a complement on a spe- 

 cific cell through a specific amboceptor, the chemical reaction being 

 due to the presence, in the chemical structure of the cell, of a re- 

 ceptor having a group of atoms haptophorous with a group of atoms 

 of the amboceptor, which, in turn, has a group haptophorous with one 

 of the complement. 



Lymph is a clear, colorless, or slightly yellow liquid of a faint 

 alkaline reaction ; in composition it closely resembles blood-serum. 

 It contains less protein, particularly less fibrinogen, the salts and ex- 

 tractives are present in about the same amount. Lymph coagulates 

 more slowly and less firmly than blood. The term " chyle " is applied 

 to the lymph of the lacteals and thoracic duct when it is clouded by 

 the fat absorbed from the food in the intestine. 



Bone is chemically distinguished from other tissues by the large 

 quantity of inorganic salts which it contains. Dried bones contain 

 about 31 per cent, of organic matter combined with 69 per cent, of 

 mineral matter. Different bones (and even different parts of the same 



