DAIRY FARMING DAIRYING — AGROTE< II NY. 181 



Leucocytes in milk and their significance, < '. V. Doane I Maryland Sta. Bui. 102, 

 pp. ?05 -■.'■■'. The author calls attention to the absence of definite knowledge con- 

 cerning tin- milk of diseased cows, describes a method devised at the station for 

 determining the number of leucocytes in milk, gives the results of numerous leu- 

 cocyte counts, reports studiesof the occurrence of fibrin in normal and diseased milk, 

 and concludes that the presence of clumps of fibrin ami leucocj tes in milk is a proof 

 that such milk came from a diseased udder. 



The Doane-Buckley method of determining the number of leucocytes in milk as 

 well as some comparisons of this method with the older one <>i* \v. R. stokes have 

 already been noted I'. S. R., 16, p. 617). The author counted the leucocytes in the milk 

 of the station herd an«l found that in a large number of samples the numbers ranged 

 from 3,000 to 1,600,000 per cubic centimeter. Even greater variations were observed 

 in the milk of individual cows of a large ami well kept private herd. In no instance 

 in either herd was the milk free from leucocytes. 



Several tests were also made of the milk from the different quarters of the ndder, 



the lowest number of leucocytes recorded being 1,000 per cubic centimeter. These 

 observations are believed to show quite conclusively that leucocytes are never absent 

 from milk, and that with most cows their numbers run into the thousands per cubic 

 centimeter. No significance is attached to even considerable variations. 



It is not believed that the mere presence of leucocytes in the milk necessarily means 

 an inflamed area in the udder, hut that the leucocytes may escape normally from the 

 Mood into the milk. However, when inflammation was evidently present the num- 

 ber of leucocytes was large. The adoption of some definite number of leucocytesasa 

 standard for indicating the presence of pus in milk istherefore believed to be by itself 

 arbitrary and unreliable. 



While studying the characteristics of pus the author observed threads identified as 

 fibrin. These were found to be most satisfactorily stained by using Delafield's hema- 

 toxylin, to which 15 per cent of carbolic acid had been added, and counter staining 

 with eosin. Such threads were also found in milk and when present in any quantity 

 large numbers of leucocytes were found collected in masses. " There can be little 

 doubt that these leucocyte masses or clumps furnish the most practical and the easiest 

 means of determining the presence of pus and the healthfulness of the milk." 



When the number of leucocytes is low the presenceof clumpsneed not he expected, 

 but when the number is high search should be made for them. "The presence of 

 fibrin, as shown by clumps of leucocytes in the blood counter, or as demonstrated by 

 stained threads, combined with an abnormal number of leucocytes, is the only satis- 

 factory proof that inflammation exists in the udder. Without the fibrin any serious 

 inflammation is to be doubted." 



Contrary to statements that the milk of cows once affected with garget is never 

 ■gain fit for use, tests by the author's method failed to show that milk after such 

 attacks is always unwholesome. 



Reference is made to the work of Babcock on the occurrence of fibrin as a natural 

 constituent of milk (E. S. R., l, p. 162), which the author believes has not heretofore 

 been established, but which can lie demonstrated microscopically in suitable prepa- 

 rations. 



Experiments with Flieg-el's apparatus for determining dirt in milk, .1 . K i hi \ 

 i Milchw. ZentbL, J ( 1905 I, No. 7, pp. 805-807).— The milk is filtered through a layer 

 of cotton previously dried at 100°. The cotton filter is then washed successively 

 with water, alcohol, and ether, and again dried to a constant weight, the difference 

 in the 2 weighings representing the amount of insoluble impurities in (he milk. Sev- 

 eral determinations art' reported. The method i- considered more satisfactory than 

 the others which have been devised tor this purpose. 



Examination of Babcock test apparatus ( Connecticut State Sta. Rpt. 1904, P f - ■>. 

 p. 44S).—Oi 151 pieces of glass apparatus tested in 1904 only 1 was found inaccurate. 



