Suppression and Prevention of Anthrax in Herds. 255 



fensive agents can not be certainly stated, yet certain indications 

 show that the eosinophile cells of the blood are presumably im- 

 portant factors in this work. The spleen as the seat of ex- 

 tensive blood changes, and as preeminently the seat of election 

 of internal anthrax is probably involved. The dogs from which 

 Bardach had removed the spleen were found to be three times as 

 susceptible to anthrax as were the dogs that had not been 

 operated on. I^ep's rats, in which he had produced mellituria 

 by the administration of phloridzin were found to be much more 

 susceptible to anthrax. This together with the habitual impli- 

 cation of the liver in internal anthrax, suggests the existence of 

 a certain protective power in the products of the healthy liver. 



The practical problem for the sanitarian- is to develope the 

 habit of producing defensive products without imperilling life. 



By Minimum Dose. Chauveau and Colin secured this in the 

 larger animals by intravenous injection of a minimum dose, — one 

 or two bacilli. This is more lasting in effect if a second and 

 stronger dose is injected some days later. 



By Weakened Virus. This has been secured by heating the 

 defibrinated blood to 55° C. for ten minutes (Toussaint); Pasteur, 

 Chamberland and Roux accomplished the same end by making 

 anthrax cultures at 42" to 43° C. in presence of air; Chauveau 

 by subjecting the virulent culture for 8 days to oxygen under 

 a pressure of 8 atmospheres at a temperature of 38° C; Chamber- 

 land, Roux and others have cultivated the bacillus in weak 

 antiseptic bouillons as phenic acid (1:600 or 1200), bichromate 

 of potash (1:2000 or 5000), sulphuric acid (2:100). 



Other methods have been followed, as growing the bacillus in 

 the blood or serum of immune animals (dog, chicken, pigeon, 

 white rat, frog). 



Of these different methods that of Pastenr has been most ex- 

 tensively adopted. The temperature of culture (42° C. ) prevents 

 the formation of spores and the duration of exposure to air 

 gradually lessens the virulence until in 12 on 3 days it is not fatal 

 to the Guinea pig and after 31 days it fails to kill the young mouse. 

 Thus preparations of varying grades of virulence, and adapted 

 to the varying susceptibility of different animals, are secured. 

 The protective inoculation is made by preference in spring, when 

 there is less chance of complication by a coincident accidental in- 



