5IO THE CONTROL OF THE MILK SUPPLY 



3. The veterinary surgeon examines the milking cows on the 

 farm, and also takes samples from any having suspicious udders. 

 These samples are taken under strict precautions as to cleanliness, 

 and sterilised bottles, etc., are again used for the purpose. These 

 samples are labelled in the same way as are the station samples, 

 and are then taken for examination to Professor Delepine. The 

 veterinary surgeon also makes a thorough examination of the 

 condition of the cowsheds, draws plans, and suggests structural 

 improvements. 



4, In examining samples of milk from suspicious cows, Pro- 

 fessor Delepine usually makes two reports : one giving the result 

 of the microscopical examination of the sediment, obtained by 

 centrifuging the sample of milk, for tubercle bacilli, and the 

 other giving the result of testing the sample of milk by inocu- 

 lation into animals. Samples of milk from cows found to have 

 suspicious or diseased udder by clinical examination, without 

 previous station samples, are examined in the same way. 



In no case is any action taken against the farmer until it has 

 been definitely proved that the milk taken by the veterinary 

 surgeon from a cow having a diseased or suspicious udder has 

 been shown to be tuberculous by one or other of these tests. 

 Control examinations are also made with the object of insuring — 

 {a) that a second case of tuberculosis has not been overlooked, and 

 {b) that the animal found has been removed from the herd. When 

 a cow with tuberculosis of the udder is found, the farmer is urged 

 by the Medical Officer of Health to slaughter the animal as soon 

 as possible. During 1902, 31 such cows were found and 16 were 

 slaughtered; the remaining 15 tuberculous cows were sold in the 

 open market.^ 



{c) Tuberculin. — In recent years the method of testing herds 

 for tuberculosis by means of tuberculin has come into vogue, and it 

 will be necessary to refer briefly to this subject. The discovery by 

 Koch, in 1890, of the production of fever, indicated by a rise in 

 temperature, in tuberculous animals into which he injected a 

 sterilised glycerine extract of pure cultures of tubercle bacilli, while 

 it produced no effect whatever when the animals were free from that 

 disease, furnished us with a simple but very reliable diagnostic 

 agent. 



How tuberculin is made. — Tuberculin is a soluble product of 

 cultures of tubercle bacilli, of which a glycerine extract is made, 



* For particulars respecting the Manchester method and its results, see 

 Reports on the Health of the City of Manchester, 1901 and 1902 (Dr Niven). 



