OPSONINS AND VACCINE THERAPY 345 



cells to the blood serum; furthermore, that, while our knowledge 

 of the blood serum, as developed at present, shows that phagocytes 

 may be aided by this in the ingesti.on of bacteria, the subsequent 

 digestion of the germs, and possibly the neutralization or destruction 

 of their intracellular poisons, is, as far as we know, largely accom- 

 plished by the unaided phagocytic cell. It is an obvious thought, 

 therefore, that, in the struggle with bacterial invaders, the leucocytic 

 defenders might be considerably re-enforced if they were furnished, 

 as directly as possible, with a further supply of the very weapons 

 which they were using in the fight with Hiss 22 conceived the plan 

 of injecting into infected subjects the substances composing the chief 

 cells or all the cells usually found in exudates, in the most diffusible 

 form and as little changed by manipulation as possible ; and he also 

 assumed that extracts would be more efficacious than living leuco- 

 cytes themselves, since if diffusible they would be distributed im- 

 partially to all parts of the body by the circulatory mechanism. 



The method of obtaining these substances as used both in animal 

 experiments and in the treatment of human subjects is at present 

 as follows: 



Rabbits, preferably of 1,500 grams weight or heavier, receive 

 intrapleural injections of aleuronat. This is prepared by making a 

 three per cent solution of starch in meat-extract broth, without heat- 

 ing, and adding to this, after the starch has gone into thorough 

 emulsion, five per cent of powdered aleuronat. This is thoroughly 

 mixed, boiled for five minutes, and filled into sterile potato tubes, 

 20 c.c. into each tube. Final sterilization is done preferably in an 

 autoclave. The rabbit injections are carried out by injecting 10 c.c. 

 into each pleural cavity in the intercostal spaces at the level of the 

 end of the sternum, in the anterior axillary line, great care being 

 exerted to avoid puncturing of the lungs. The rabbits are left 

 for twenty-four hours, at the end of which time a copious and very 

 cellular exudate will have accumulated in the pleural cavities. This 

 is removed, after killing the animals with chloroform, by opening 

 the anterior chest wall under rigid precautions of sterility, and 

 pipetting the exudate into sterile centrifuge tubes. Immediate cen- 

 trifugalization before clotting can take place then permits the 

 decanting of the supernatant exudate fluid. To the leucocytic sedi- 

 ment is then added about 2 c.c. of sterile distilled water, and the 



- Hiss, Jour. Med. Ees., N. S., xiv, 3, 1908. 



