lo Feb.. 191^-] Diseases i>f Farm Animals. 85 



grave or infected soil ; also grass or plants springing from deeplv-buried 

 seed and pushing up through rain-loosened soil may carry bacilli to the 

 surface on their growing leaves. Again, anthrax may occur in very dry 

 seasons when infected water-holes, swamps and morass land dry up and 

 leave the germ-mixed mud accessible to stock. A growth of vegetation 

 springs up on the mud coating, and stock often pull up such vegetation 

 by the roots and so run further risk. Flies and insects of various kinds are 

 also much more numerous during the dry summer season, and they are 

 undoubted carriers of contagion. 



Method of Infection. — It will have been gleaned from what has been 

 said about infection from pasturage that one of the principal ways in 

 which the germ gains entrance to the system is in the food by ingestion. 

 In addition to pasture, hay or other fodder grown on infected land is a 

 frequent cause of anthrax breaking out on previously uninfected properties. 

 In New Zealand, anthrax in sheep has been traced to the feeding of grow- 

 ing root crops, in which case the likelihood of ingesting soil along with 

 the food is very great. Root crops that have been manured with bone- 

 dust supposed to have been contaminated with anthrax germs have been 

 particuarly blamed. Since the investigation of this phase of the subject 

 by Professor Gilruth, when Government Veterinarian in New Zealand, im- 

 ported Indian bonedust has been held responsible for a number of out- 

 breaks in Victoria and elsewhere throughout Australia. 



Inoculation is another form of infection, flies and insects conveying 

 the germs from anthrax carcases to wounds and abrasions on other animals. 

 Inoculation may also occur through accidental wounds made with knives 

 and instruments previously used on an anthrax carcase ; in fact, this is 

 the most common way in which man becomes infected with the form of 

 anthrax known as "malignant pustule." 



It is questionable whether the disease in animals is ever caused by 

 Inhalation, but in man the pulmonary anthrax called " woolsorters' 

 disease" is most likely caused through inhalation of the particles con- 

 taminated with anthrax germs which rise when dried skins, hides and wool 

 are being handled. 



Forms of Anthrax and Symptoms. — As a general infection anthrax 

 occurs in hyper-acute, acute and siib-acute forms. The first of these is 

 more usually described as Apoplectic or Fulminant anthrax. The animals, 

 cattle or sheep mainly, are affected suddenly without premonitory symp- 

 toms ; they have convulsions and die in the course of from a few minutes 

 to an hour. The earlier cases in the anthrax outbreak at Keilor,_ Victoria, 

 in the beginning of 1903 were of this form, some of the cows being found 

 dead within an hour of their having been observed feeding, and apparently 

 perfectly well. Others w-ere seen to suddenly stop feeding, look round 

 wildly, stagger and fall as if in a fit and die after struggling for a few 

 minutes. The fulminant form of anthrax appears to afford an illustration 

 of the phenomenon observed by various investigators that the bacilli are 

 less numerous in the blood in proportion to the more rapid course of the 

 infection. Quite often in these cases the bacteriological examination of 

 the blood gives negative results because the bacilli are located or colonized 

 in one particular organ or spot ; they have not had time to multiply to an 

 extent sufficient to pervade the whole body before death results from the 

 lethal effects on the central nervous system of the anthrax toxin formed 

 locallv. 



