ANIMAL DISEASES. I39 



in one or more of the animals. Even within modern times, 

 inflammation of the udder was very generally ascribed to what 

 were vaguely called " chills," and it was seriously believed that 

 a draught plajdng on the cow's hind quarters was likely to be 

 followed by an attack of garget. 



At the present day, it may safely be asserted that nearly all 

 cases of inflammation of the udder are caused by the multiplica- 

 tion of bacteria either in the so-called milk cistern or in the tissue 

 of the udder itself. It is already a matter of popular knowledge 

 that the tubercle bacillus is responsible for one form of garget, 

 and that form is invested with quite special importance because 

 the milk secreted by the udder may be a cause of infection to 

 human beings. It has also been maintained that certain other 

 forms of garget are important in relation to human health, 

 especially in connection with outbreaks of sore throat. It must 

 be recognised, hov/ever, that putting aside all question of danger 

 to human beings, inflammation of the udder has a considerable 

 economic importance because of the temporary or permanent 

 loss of milk from the affected quarter or quarters of the udder. 

 From this point of view even what are called sporadic cases are 

 in the aggregate important. The term "sporadic" as here 

 employed is intended to cover the occasional single cases which 

 occur from time to time in nearly every herd, and is used in 

 opposition to those cases which occur in the form of actual out- 

 breaks involving a considerable or even a large proportion of the 

 whole herd. It must be admitted, however, that the distinction 

 between these two classes of cases is not sharp, for, given the occur- 

 rence of a single case, one has no assurance that the disease may 

 not be spread to other cows if all precautions are neglected. 

 With the notable exception of tuberculous inflammation of the 

 udder, the general method of infection in mastitis is by way of 

 the canal of the teat, and the milker's hand is the agent that 

 transfers the baccilli from the diseased to the previously healthy 

 cows. 



While the views just expressed now find general acceptance, 

 there is stiU a great lack of precise information regarding the germs 

 that are responsible for different cases of inflammation of the 

 udder, and the best methods of prevention and treatment. This 

 is reflected in the inadequate account of the condition given in 

 even the most recent editions of the standard text books dealing 

 with diseases of animals. 



Although a systematic investigation of inflammation of the 

 udder was only begun during the past year, occasional outbreaks 

 have been dealt with as far as the resources of the Institute allowed 

 in previous years, and the experience thus gained disclosed the 



