23 



and 4 small injections of the living culture "381" at intervals of 8 to 10 

 days. This rabbit was now injected under the skin of the back with 4 

 c. c. of a suspension of streptococcus "381" and at the same time a nor- 

 mal rabbit weighing 2100 G. was injected in the corresponding locality 

 with 2 c. c. of the same streptococcus suspension. The normal rabbit 

 died on the 3rd day while the immune rabbit showed no signs of sickness 

 except that it lost 150 G. in weight, which was regained at the end of 

 one week. 



Experiments with rabbit leucocytes in immune serum in vitro. Ex- 

 periments were now undertaken to make a further study of the mechan- 

 ism of this immunity than has already been made by.Neufeld and Rimpau 

 and others. 



An immune rabbit and a normal rabbit were each bled 5 c. c., the 

 bloods defibrinated, divided into two equal quantities and leucocytes 

 added to each blood. One portion of each blood received leucocytes 

 from the normal rabbit and the other portion received washed leucocytes 

 from the immune rabbit. The whole blood instead of the serum alone 

 was used because rabbit blood contains only a very small number of 

 polymorphonuclear leucocytes which may be neglected, and it has been 

 found that smears from tubes containing leucocytes in blood are more 



TABLE 13. 



PHAGOCYTOSIS OF STREPTOCOCCI BY NORMAL AND BY IMMUNE RABBIT LEUCOCYTES JN 

 NORMAL AND IN IMMUNE RABBIT BLOOD. 



Strepto- Phagocytosis by normal leucocytes in : 



cocci. Normal Blood. Immune Blood. 



Laura* G.2 14. 



381 2.2 4.8 



Joe R. 4.4 7.G 



Stuart 1. 4.0 



Puerperal 1. 1.6 



Phagocytosis by normal leucocytes in : 



Normal Blood. Immune Blood. 



Laura 5.5 15.2 



381 1.7 5. 



Joe R. 5.3 7.2 



Stuart 1. 4.2 



Puerperal 5. 2.5 



**Sources of Streptococci: "Laura" from a* scarlatinal otitis media, and 

 used to immunize the rabbit, the serum of which was used hi this experiment; 

 "Joe R." from a scarlatinal sore throat ; "381" from pericardial fluid of a scarla- 

 tinal body ; "Stuart" from a case of erysipelas and "Puerperal" from a blood cul- 

 ture of a case of puerperal sepsis. All were only of medium virulence. 



