STUDY OF ANTISTREPTOCOCCIC SERUM. 133 



difficult to find them microscopically. It is quite probable that 

 these organisms have been taken up by leucocytes in the blood, since 

 the serum of animals that have received preventive serum shows no 

 bactericidal property that apparently would offer resistance to the 

 growth of the micro-organism in the circulating blood. We know, 

 to be sure, that when small amounts of streptococci are inoculated 

 into a region containing many leucocytes (a prepared peritoneum) 

 they are rapidly taken up and their growth inhibited. Moreover, 

 at autopsy of such rabbits after death there are frequently to be 

 found in the internal organs (lungs or spleen) leucocytes, particularly 

 mononuclears, containing numerous streptococci. 



A subcutaneous inoculation is the one most easily tolerated by 

 animals that have received serum. No edema occurs at the point 

 of inoculation (except with inoculations in the ear), which renders 

 the study of this condition rather difficult. The bacteria do not pass 

 into the blood and it is probable that the cells of the lymph spaces 

 in the glands have an important function in defending the body. 

 We have many things still to consider on this point. Denys and 

 Leclef, particularly by studying the effects of subcutaneous inocu- 

 lations in the ear, have established the fact that the immunity is 

 due to phagocytosis. Inoculation into the aqueous humor is dan- 

 gerous. The very smallest amount of streptococci when introduced 

 here increases rapidly. The influx of leucocytes is slow, not occur- 

 ring to any extent under 24 hours, and is not sufficient to protect the 

 animal for any length of time. Later on well stained chains of strep- 

 tococci surrounded by an areola are found free amid leucocytes that 

 contain few bacteria; a generalized infection finally takes place. 

 The serum injected into such a rabbit, however, was very active; 

 as it protected another rabbit in the same close against the sub- 

 cutaneous inoculation of 0.25 of a cubic centimeter of a young and 

 very virulent culture. 



