ix PEOTECTIVE INOCULATION 265 



of certain experiments with the clear filtrate after removal 

 of the bacilli. 



2. Action of Sterilised Bacillary Bodies. — The bodies 

 of the sterilised bacilli were employed in the form in which 

 they occur in the Haffkine prophylactic. The manner of 

 obtaining them was very simple. As was mentioned on 

 a former page of this chapter, the prophylactic was 

 preserved by me in sealed tubes without the addition of 

 any preservative, each tube containing 30, 32, and 36 cc. 

 When left standing upright all the bacillary bodies settle at 

 the bottom of the tube, whereas the fluid above becomes and 

 remains quite limpid. From such a tube — after opening 

 it by breaking the sealed end — the fluid is siphoned off, a 

 process very easily achieved. The remaining sediment is 

 then distributed in salt solution in amount equal to the 

 quantity of broth siphoned off. Of this emulsion 10 cc. 

 are used subcutaneously per rat. As a matter of fact, 

 the 30 to 36 cc. of the fluid in a given tube, salt solution 

 plus bacillary sediment, were used for three rats. The 

 result was complete protection in each instance by this 

 preliminary injection against the subsequent injection of 

 living culture. I have made two series of such experi- 

 ments, each comprising three prepared rats and one 

 control, and in both series the result was positive, viz. 

 death of the control rat and survival of the prepared 

 animals. 



3. Action of the Filtrate per se of Haffkine 7 s Pro- 

 phylactic. — From what has just now been stated, viz. 

 that practically the bacillary sediment and the complete 

 Haffkine prophylactic are equally protective, it was to be 

 inferred that the fluid itself — i.e. the broth in which the 

 bacilli had been growing, but minus the bacilli — is of no 



