290 BIOLOGY: GENERAL AND MEDICAL 



resemblances found to obtain among different kinds of 

 animals. The test for determining it is found in the 

 phenomena of specific precipitation and hemolysis. 



The studies of the blood leading to present knowledge 

 began with the work of Creite, who in 1869, found that 

 heterologous bloods not infrequently caused hemolysis. 

 Landois in 1875 found that the transfusion of heterolo- 

 gous blood into an animal not infrequently caused its 

 death. Bordet, in 1898, found that when guinea-pigs 

 were given frequent intraperitoneal injections of defibri- 

 nated rabbits' blood, their blood serum acquired the 

 property of dissolving rabbits' blood corpuscles in vitro 

 (hemolysis); Ehrlich and Morganroth, in 1899, showed 

 the mechanism of such blood corpuscle solution. Tchis- 

 towich, in 1899, showed that eel's serum injected into 

 animals produced a reaction in which the animals ac- 

 quired immunity to its poisonous effects, as well as their 

 serum the power to form a precipitate when added to 

 the eel's serum in vitro. Uhlenhuth, in 1900-1901, found 

 that the precipitation resulting from the addition of the 

 immune serum to the antigen by whose stimulation 

 the immune character of the serum was developed, was so 

 specific as to be of use in forensic medicine for the cer- 

 tain differentiation of blood stains. Wassermann and 

 Schutze, in 1900, prepared a serum by injecting rabbits 

 with human blood, and tested its precipitating proper- 

 ties upon twenty-three different kinds of blood, finding 

 the precipitate most marked the nearer the animal was 

 related to man. 



The work of Nuttall and his associates, " Blood-immu- 

 nity and Blood-relationship," appeared in 1904, and 

 dwells exhaustively upon the reaction of precipitation 

 in all its phyletic relations. 



Through a study of the specific precipitins we learn 

 that though the reaction is specific that is, takes 

 place in greatest quantity and with greatest rapidity 

 when the antibody is permitted to act upon its own 

 antigen, the antigens derived from closely related ani- 



