SPECIFIC BACTERIAL PRODUCTS 453 



normal opsonins that "normal human serum may contain 

 bactero-opsonins with marked specific affinities. The results of 

 experiments indicate that the bactero-opsonins and hemop- 

 sonins in human, rabbit and dog serum may be distinct sub- 

 stances, at least in part, and that normal serum may contain 

 several more or less distinct opsonins for alien red corpuscles. ' ' 

 The opsonic index, however, is not considered by many 

 pathologists trustworthy, but the efficiency of autogenic vac- 

 cine, in certain cases at least, has been well established. How 

 generally it can be applied with success is not known. Vaccine 

 treatment is still in the experimental stage. 



then scraped off and sterilized. They are then, in a moist condition, 

 placed in a mortar and thoroughly ground into a paste. While grind- 

 ing, salt solution (1.5 cent) is gradually added until a thick emul- 

 sion appears. This emulsion may be diluted and larger clumps 

 separated by centrifugalization. 



"(3) The leucocytes are obtained by bleeding from the ear or 

 finger directly into a solution containing eighty-five hundredths per 

 cent to one per cent of sodium chlorid and five-tenths to one and 

 five-tenths per cent of sodium citrate. Ten or fifteen drops of blood 

 to 5 or 6 cc. of the solution will furnish sufficient leucocytes for a 

 dozen tests. This mixture is then centrifugalized at moderate speed 

 for five to six minutes. At the end of this time, the corpuscles at 

 the bottom of the tube will be covered by a thin grayish pellicle, the 

 buffy coat, consisting chiefly of leucocytes. These are pipetted off 

 with a capillary pipette (by careful superficial scratching move- 

 ments over the surface of the buffy coat). 



"There being, of course, no absolute scale for phagocytosis, 

 whenever an opsonin determination is made upon an unknown 

 serum, a parallel control test must be made upon a normal serum. 

 This normal is best obtained by a "pool" or mixture of the sera of 

 five or six supposedly normal individuals. 



"The three ingredients serum, bacterial emulsion, and leuco- 

 cytes having thus been prepared, the actual test is carried out as 

 follows: Capillary pipettes of about six or seven inches in length 

 and of nearly even diameter throughout, are made. These are fitted 

 with a nipple and a mark is made upon them with a grease-pencil 

 about 2 to 3 cm. from the end. Corpuscles, bacteria and s"erum are 

 then successively, in the order named, sucked into the pipette up to 

 the mark, being separated from each other by small air-bubbles. 

 Equal quantities of each having thus been secured, they are mixed 

 thoroughly by repeatedly drawing them in and out of the pipette 



