are not phagocyted at all by the normal animal, but after one 

 or two inoculations of this or^-anism the opsonins for pneumc- 

 cocci increase and can be still further increased by subsec^uent 

 injections, provided a lethal dose is not administered. Once 

 this quantity is given, however, there is a rapid decline in 

 phagocytic activity, the zero mark ordinarily being reached 

 some time before the death of the animal. 



The variation in the opsonic curve for* S. aureus re- 

 quires some explanation. Up to December 3 the curve foi' this 

 organism had remained normal, but at this time a culture of 

 Pneumococcus I, contaminated with* S. aureus was injected and 

 five days later the dog's blood showed an increase in opsonins 

 for staphylococci. This organism was almost immediately over- 

 come, for it W3 s never obtained in subsequent blood cultures. 

 The increased opsonic activity for staphylococci continued a 

 few days, but gradually decreased until at the end of a month 

 the index w&s again normal. However, on January 20 pneumo- 

 cocci appeared in the blood and the reaction against this 

 homologus antigen resulted in a non-specific increase in the 

 residue of antibodies remaining from the previous staphylo- 

 coccus inoculation. This w& s immediately reflected by a rise 

 in the opsonic curve for staphylococcus. These observations 

 are in agreement with the findings of Beiling (21). 



Experiment 2. — This experiment is presented as a 

 parallel to the preceeding experiment and was performed through- 

 out in a similar manner, except that it was found possible to 



(14) 

 ♦ Staph, aureus. 



