AGGLUTINATION AND DISSOLUTION. 139 



Sixth : — The phenomena mentioned do not occur if normal guinea- 

 pig serum is used instead of the serum from a guinea-pig that has 

 been treated with frequent injections of defibrinated rabbit blood. 

 Normal guinea-pig serum has only a very slight clumping effect on 

 rabbit corpuscles and its destructive power against them is practi- 

 cally nil. 



Seventh : — The specific serum of a treated guinea-pig has no effect 

 on the defibrinated blood of a normal guinea-pig. It has, moreover, 

 no effect on the red blood cells of the pigeon. It agglutinates ener- 

 getically rat and mouse corpuscles, but no more so than normal 

 guinea-pig serum. This guinea-pig serum, which affects rabbit 

 blood, has slightly more destructive properties for rat and mouse 

 corpuscles than does normal guinea-pig serum ; but the destruction 

 of corpuscles in a mixture of this active serum and rat or mouse 

 blood is very much less complete and rapid than in a mixture 

 of the serum with rabbit corpuscles. We intend trying the effect 

 of this serum on the corpuscles of a great number of species in 

 order to determine just how far the phenomenon is specific; the 

 specificity, however, from the data that we have already given 

 would seem to be very distinct, if not absolute. 



Eighth: — If a small amount (2 c.c. for example) of defibrinated 

 rabbit blood is injected into the peritoneal cavity of a treated guinea- 

 pig (that is a guinea-pig that has received several injections of 

 rabbit blood) the corpuscles are rapidly destroyed. The fluid with- 

 drawn from the peritoneal cavity ten minutes later is red and limpid. 

 The corpuscles remain intact much longer if injected subcutaneously. 

 If such an injection is made into the peritoneal cavity of a normal 

 guinea-pig the corpuscles remain unchanged and are finally taken 

 up by the macrophages. 



Ninth: — If rabbit blood plus a small amount of active serum 

 previously heated to 55 degrees, is injected into the peritoneal 

 cavity of a normal guinea-pig a similar destruction of corpuscles 

 occurs. 



Tenth : — As might be expected an active serum with so marked an 

 effect on rabbit corpuscles is toxic for this animal. Two cubic centi- 

 meters injected into the ear vein is fatal. We shall later return 

 to a discussion of the symptoms and lesions which such injections 

 cause. 



