SOILS 393 



produces tetanus lives in the soil, and from the fact of it 

 being an anaerobic parasite it would appear to develop at 

 some distance from the surface. The liability of equines 

 to tetanus may depend entirely on the greater facilities for 

 infection from the soil — as, for example, in wounds of the 

 feet — than exists in man. We do not believe, as is asserted 

 by medical writers, that it was originally a disease of the 

 horse, but there is no difficulty in understanding the greater 

 liability of equines to infection. 



Malignant GEdema. — The bacillus of this disease is 

 readily isolated from garden mould. It produces a fatal 

 disease in guinea-pigs, rabbits, and mice, and has been 

 observed in the human subject, after compound fractures, 

 accompanied by a rapidly spreading oedema with emphysema 

 of the tissues. The same condition may occur in the 

 horse following castration. 



Anthrax is generally regarded as a soil disease, but it can 

 only be so in the sense that the soil receives the germs 

 from a previous case, either by the death of the animal, or 

 by spores being carried on to the land during floods, and in 

 other ways. 



It is quite true that certain lands possess an unenviable 

 notoriety for producing anthrax, but that is only as the 

 result of previous or persistent infection. It is not a soil 

 disease, but the organism can live and multiply in the soil 

 as apart from the animal body, provided the needful 

 temperature, moisture, and oxygen are available. In this 

 way pastures become infected from the blood or discharges 

 of previous cases, and there is evidence to show that the 

 infection may remain very persistent. This question will 

 be referred to again in the chapter dealing with the 

 eradication of infectious diseases. 



Quarter-Evil is another affection intimately connected 

 with certain pastures, for fuller information on which the 

 section dealing with this disease should be consulted. 



Epizootic Lymphangitis in horses is mentioned in con- 

 nection with soil diseases, as it is probable soil infection is 

 a common cause of inoculation. We do not know whether 



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