140 AGRICULTURAL RESEARCH AND THE FARMER : 



difficulties which He in the way of investigation. When assist- 

 ance in deahng with an outbreak is requested, the first point to 

 be determined is the actual cause of the condition, and with that 

 object the milk has to be examined in order to determine what 

 organisms if any are present in it. At the very outset difficulty 

 arises from the fact that the normal udder generally appears 

 to yield milk containing bacteria, and such bacteria may multiply 

 after the milk has been withdrawn from the udder, and have 

 become numerous before the sample has reached the laboratory. 

 In such circumstances, the difficulty in detecting the particular 

 organism responsible for the mischief is greatly increased. 

 Efforts are being made to discover some substance which when 

 added to the milk at the time of milking might prevent the 

 multiplication of bacteria in transit without actually destroying 

 them. This difficulty of course disappears when the milk can 

 be examined on the spot, but a complete bacteriological examina- 

 tion of milk is scarcely possible except in a fully equipped 

 laboratory. 



It may be said, however, that in spite of these difficulties, it 

 is generally possible promptly to come to a conclusion as to 

 what is the particular organism causing the inflammation when the 

 udder is obviously diseased and the milk is altered in appearance. 

 It is only when this point has been determined that one can pro- 

 ceed to consider methods of cure or prevention. Dealing in the 

 first case with prevention, it will be obvious that if the further 

 spread of the disease is to be stopped, steps must be taken to hinder 

 the transference of bacilli from the infected to the healthy cows, 

 especially by the hands of milkers. This applies specially to 

 the visibly diseased cows, but unfortunately in the very con- 

 tagious form of garget it has been found that precautions of this 

 nature, when confined to the visibly diseased animals, are not 

 effectual in preventing the spread of the disease. The explana- 

 tion of this failure lies in the fact that in its early stages infection 

 is not manifested by any decided change in the appearance of the 

 milk or by any distinct alteration in the quarter itself. In other 

 words, the difficulty that has to be overcome is that of early 

 diagnosis. 



In some outbreaks already dealt with an attempt has been 

 made to reach this object by laborious repeated tests of samples of 

 milk from all the apparently healthy cows in the herd, and in 

 this way fairly satisfactory results have sometimes been obtained. 

 The diagnosis in these cases was reached by what may be called 

 bacteriological methods, but it has recently been suggested that 

 it may be possible to detect infections of the udder at a very 

 early stage because of alterations in the chemical reaction of the 



