Suppression and Prevention of Anthrax in Herds. 217 



hard work, in advanced gestation, in full milk, in extreme youth, 

 or in ill health. To secure the best results it should be repeated 

 with a stronger preparation 12 to 15 days after the first injection. 

 The acquired immunity lasts a year and over, and it is probably 

 perpetuated by new and non-fatal doses taken in casually, on the 

 anthrax pastures. Hundreds of thousands of live stock in all 

 parts of the world have been treated in this way with the result 

 of reducing a mortality of two, five or ten per cent, to insignifi- 

 cant proportions. It can only be safely adopted on anthrax lands, 

 as elsewhere it may lead to the stocking of new areas with a 

 malignant germ which in young and susceptible animals reac- 

 quires its original virulence, 



It can never be safely ignored that we are dealing with the 

 living seed of a most deadly infection. Though robbed of a 

 large part of its virulence by artificial culture at 107:5° F., yet 

 many accidental conditions, contribute to a relapse to its original 

 potency, and when it has once killed a victim, the reacquired 

 virulence is usually persistent. If the virus employed for pro- 

 tective purposes in cattle and sheep, is inoculated on Guinea pigs 

 of 1 to 30 days old, from these on those of several months, and 

 from these last on sheep, the virulence is constantly and persistently 

 enhanced. The same is true of the microbe which is inoculated 

 on a succession of pullets of steadily encreasing ages (Roux 

 and Chamberland), or on a succession of pigeons (Met- 

 chnikoff). The germs reinforced in potency in any such way 

 are liable to be the starting points for dangerous infections in 

 animals and permanent contamination of soils and waters. 

 Fortunately an occurrence of this kind is rare, yet with a wide 

 application of the Pasteurean inoculation the opportunities also 

 are great, and with the free sale and distribution of the mitigated 

 virus (anthrax " vaccine"), the evil may grow indefinitely. The 

 method departs from the ideal one, aimed at a final extinction of 

 the disease, and accepts in place a mere temporary protection of 

 the herd or flock, and though in this affection eradication cannot 

 always be secured, every effort should be made to gain it and 

 above all to prevent an encrease of the area of infection. 



Technique. The weakened virus (1st " vaccin") is sold in 

 tubes holding enough for 100, 200, or 300 sheep. Of this 

 }£ cc. is injected subcutem on the inner side of the thigh of the 



