THE LTSINS. 131 



No. 10 were freed from their own serum and washed with physiolog- 

 ical salt solution they were found to be as susceptible to the serum 

 of goat A as they were before. 



Goat B was treated in exactly the same manner as goat A. How- 

 ever, it was found that in this case no isolysin appeared in the serum 

 until the fifteenth day, when its appearance was sudden. During 

 the first fourteen days after the injection the erythrocytes of goat B 

 remained highly susceptible to the isolysin in the serum of goat A ; 

 and, strange to say, this susceptibility continued even after the 

 serum of goat jB manifested its hemolytic properties. It was further- 

 more found that the erythrocytes of certain goats were susceptible to 

 the isolysin of goat A and insusceptible to that of goat B. It ap- 

 pears from this that there are different isolysins and it was also found 

 that anti-isolysin A was wholly without action against isolysin B. 



A third goat, C, received at the same time a like amount of the 

 same blood as B, and first furnished a hemolysin on the seventh day. 

 This hemolysin was also found to be an isolysin, but different from 

 that of either A or B. These experiments demonstrated that the 

 exact nature of the isolysin depends upon the individual character- 

 istics of the animal in which it is formed. A fourth goat, D, fur- 

 nished an isolysin which dissolved the blood corpuscles of B and C, 

 but was without effect upon those of A. The sera of A, B and C 

 dissolved sheep's corpuscles, while the serum of D was without 

 effect. 



Ehrlich compares the intermediary body with diazo-benzaldehyde, 

 which by means of its diazo group is capable of combining with a 

 series of bodies, such as aromatic amins, phenols, keto-methyl bodies, 

 etc., while by means of its aldehyde group it may combine with a 

 different series such as the hydrazins, ammonia radicles, and hydro- 

 cyanic acid. Phenol and hydrocyanic acid will not directly combine, 

 but with diazo-benzaldehyde acting as an intermediary body, these 

 two substances can be brought into combination. Pushing this 

 comparison further, we may say that the aromatic body, or the 

 phenol, represents a constituent of the blood corpuscle. The diazo- 

 benzaldehyde is the intermediary body, while the poisonous hydro- 

 cyanic acid constitutes the complement. As has been stated, the 

 intermediary body has two haptophorous groups. By means of one 

 of these it combines with the receptor of the cell, while by means of 

 the other it combines with the complement. The former may be 

 designated as the cytophil group, while the other may be distin- 

 guished by the designation of complementophil. It should be 

 understood that there are probably many varieties of intermediary 

 bodies, and there may be two or more in a given blood serum. In 

 fact, Ehrlich has demonstrated the presence of two or more kinds of 

 intermediary bodies in the same serum. The serum of a rabbit 

 which has been immunized to ox blood has a hemolytic action not 



