vin AGGLUTINATION OF B. PESTIS 233 



cubic millimetres of blood serum. At the same time 100 

 cubic millimetres of plague emulsion were injected into 

 control guinea-pig No. 12. 



Both guinea-pigs developed big buboes. The control 

 guinea-pig died on the thirteenth day, the other guinea- 

 pig which had received plague culture plus blood serum 

 died on the seventh day, both of plague; that is to 

 say, the control animal died later than the other. The 

 blood serum had therefore had no effect whatever of 

 neutralising the fatal dose of plague culture. 



(2) July 29. — Guinea-pig No. 17 was injected with a 

 mixture of 100 cubic millimetres of plague emulsion and 

 50 cubic millimetres of blood serum. At the same time 

 a control guinea-pig No. 18 was injected with 100 cubic 

 millimetres of plague emulsion alone. 



Guinea-pig No. 17 developed no bubo, and remained 

 quite lively and well. Guinea-pig No. 18, on the other 

 hand, showed distinct bubo on the third day ; this en- 

 larged till the eighth day, then gradually diminished and 

 disappeared, the animal quite recovering. This experi- 

 ment is therefore faulty in this, that the control animal 

 did not succumb to plague, the dose injected not proving 

 a fatal dose. But the experiment apparently indicates 

 that some inhibiting effect was produced by mixing the 

 blood of the prepared guinea-pig with a dose of plague 

 culture that served in a control animal to cause a distinct 

 bubo. Referring to the table, it will be seen that at the 

 date on which the blood serum was obtained from the 

 guinea-pig No. 1 this animal had been injected three 

 times with sterile culture, and seven times with small 

 doses of living culture of plague bacillus, and that 

 therefore by this time its blood seemed to contain 



