306 BIOLOGY: GENERAL AND MEDICAL 



animals. His tests for determining it were the occurrence 

 of 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 or so- 

 lution of the red blood corpuscles of the animal into which 

 the blood was injected. Landois, in 1875, found that the 

 transfusion of heterologous blood into an animal not in- 

 frequently caused its death. Bordet, in 1898, found that 

 when guinea-pigs were given frequent intraperitoneal in- 

 jections of defibrinated rabbits' blood, their blood serum 

 acquired the property of dissolving rabbits' blood cor- 

 puscles in vitro (hemolysis); Ehrlich and Morgenroth, in 

 1899, showed the mechanism of such blood corpuscle solu- 

 tion. Tchistowich, in 1899, showed that eel's serum in- 

 jected into animals produced a reaction in which the ani- 

 mals acquired 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- 

 mals and plants have sufficient chemical or physiologi- 



