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. 

 ^ he 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. 



