132 



Dr. A. E. Wright and Capt. S. B. Douglas. [Jan. 11, 



extremely characteristic involution forms* such as Ave have not seen 

 since we worked with freshly isolated plague cultures in Bombay in 

 connection with the Indian Plague Commission. So typical were the 

 involution forms of the ingested plague bacilli, that we should not 

 hesitate to employ the method of phagocytosis as an aid to diagnosis in 

 the case of a doubtful plague culture. 



Experiments on the Opsonic Power of Human Blood in 

 Eelation to Micrococcus Melitensis. 



Experiment 1. 

 A. 



S. B. D.'s unheated serum 3 vols. 



S. E. D.'s washed corpuscles . . 3 „ 



Suspension of Micrococcus Melitensis 1 PJ 



Phagocytic index (10 P.W.B.C.), 26'9. 

 B. 



S. B. D.'s heated seruui 3 vols. 



S. B. D.'s washed corpuscles. . . = 3 „ 



Suspension of Micrococcus Melitensis 1 



Phagocytic index (10 P.W.B.C.), 9'2. 



Experiment 2. 

 A. 



A. E. W.'s unheated serum 3 vols. 



A. E. W.'s washed corpuscles 3 ,, 



Suspension of Micrococcus Melitensis , . 1 „ 



Phagocytic index (21 P.W.B.C.), 10'0. 

 B. 



A. E. W.'s heated serum 3 vols. 



A. E. W.'s washed corpuscles 3 „ 



Suspension of Micrococcus Melitensis 1 vol. 



Phagocytic index (21 P.W.B.C.), 2-4. 



Experiment 3. 

 A. 



S. E. D.'s heated serum 3 vols. 



A. E. W.'s washed corpuscles 3 ,, 



Suspension of Micrococcus Melitensis 1 vol. 



Phagocytic index (21 P.W.B.C.), 12"9. 



* It may be observed that our plague culture — like other plague cultures 

 which have been cultivated on artificial nutrient media for a number of genera- 

 tions — has altogether lost the property of developing in a spontaneous manner the 

 involution forms which are characteristic of freshly isolated plague cultures. 



