THEORIES OF IMMUNITY. 



animal — a hemolytic or globulicidal property 

 was developed. A specific example is that of 

 using the blood corpuscles of a rabbit for injec- 

 tion into a goat; in a short time there appears in 

 the goat's blood an antibody to the rabbit's corpus- 

 cles, which will destroy those corpuscles whenever 

 it is brought in contact with them. This hemo- 

 lytic property, it was also found, would disappear 

 upon heating the serum containing it for one- 

 half an hour to fifty-five degrees Centigrade. 

 The very remarkable fact was, however, brought 

 out that it would reappear upon the addition to 

 the heated serum of a little fresh serum, although 

 this fresh serum itself possessed no hemolytic 

 property. 



These are similar to the occurrences going on 

 in Pfeiffer's phenomenon (of bacteriolysis), and 

 with others formed the basis of an extension of 

 Ehrlich's theory to explain what is seen to occur 

 in immunity against infection. 



In explanation of the facts seen in hemolysis, 

 Bordet, and Ehrlich as well, suppose that there 

 must be two bodies present to permit the com- 

 pletion of the reaction. One of these exists in 



68 



