191 1.] Summary of Agricultural Experiments. 1017 



been known for many years that cellular elements occur in milk, 

 and that, in certain circumstances, such as an attack of mastitis 

 or inflammation of the udder, they increase very largely in number, 

 They have been regarded as leucocytes or pus cells, and attempts have 

 been made to diagnose mastitis by estimating the number of cells 

 present. This investigation was undertaken on behalf of the British 

 Dairy Farmers' Association for the purpose of getting further 

 information as to the nature of the cells and the causes of increases in 

 their number. Samples of milk were obtained from five farms, six 

 cows being selected at each, and their mixed milk was examined 

 weekly for the greater part of the lactation period, with 

 special examinations of the individual milk of cows that developed 

 any affection of the udder. The investigation was made by counting 

 the number of cells in the milk, and by microscopic examination 

 of them, an improved method of staining the cells for this latter 

 purpose being adopted. The opinion formed by the investigators is 

 that an increase in the number of cells does not admit of any inference 

 of the existence of a diseased condition of the cows supplying the milk. 

 The udder is an organ so open to stimuli of a varied nature, and 

 yet showing practically only one form of response to such stimuli, 

 that the cause is not to be diagnosed from the effect produced. With 

 regard to the nature of the cells they find that the vast majority differ 

 materially from leucocytes, and conclude that they are not pus cells 

 derived from diseased tissues. 

 - ■ Prevention of "Struck " in Sheep (Jour. South-Eastern Agric. Coll., 

 Wye, No. 18, 1909). — A method of protecting sheep against " struck," 

 which was used with success by the Departmental Committee on 

 Louping 111 and Braxy against those diseases, has been tried for two 

 years by Mr. T. W. Cave. These latter are bacterial diseases which 

 occur almost entirely at a particular time of the year. Dr. Hamilton 

 found that during the remainder of the year the blood of sheep has a 

 distinct bactericidal action and destroys the bacteria that are the cause 

 of these diseases when they gain access to the sheep. In addition, those 

 sheep which have thus overcome the disease are rendered immune, and 

 resist its attack during the dangerous period of the year. 



" Struck " is also a disease that occurs at one particular season, 

 generally during March, April, and May, and this suggested a trial 

 of the treatment. This consists in giving to sheep in the safe period 

 of the year drenches of a culture of the bacilli in glucose broth. During 

 January, 1908, 255 sheep were each given two doses with a fortnight's 

 interval. The records kept by the shepherds showed that the sheep 

 were protected against struck for two months after the second dose. 

 During these two months not a single treated sheep died from "struck," 

 while fourteen of the untreated animals died from the disease. Unfor- 

 tunately the immunity did not last sufficiently long to carry the sheep 

 safely through the whole of the dangerous season. In order to lengthen 

 the time of immunity in 1909 a much larger amount of the culture 

 was given in three doses, the last being given on February 25th, five 

 weeks later and nearer to the dangerous season than the year before. 

 The number of sheep treated was 190, and they were put, with 190 

 untreated sheep, on land known to be dangerous. Unfortunately for the 

 trial the mortality from "struck" was very light this spring, but four 



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