New York Agricultural Experiment Station. 123 



Haring, 10 Harris, 11 Russell and Hoffmann/ 2 Bergey, 13 Kendall, 14 

 Pennington and Roberts, 15 Miller, 16 Stone and Sprague, 17 Campbell, 18 

 Hastings, Hammer and Hoffmann, 19 Jordan, 20 Heinemann, Luck- 

 hardt and Hicks, 21 Lewis, 22 Ross, 23 Scannell 24 and others. 



In 1910, Prescott and Breed 25 suggested a method of counting 

 these body cells in milk directly without the use of the centrifuge. 

 In this method, stained smears of a small drop of milk (0.01 cubic 

 centimeter) were made on an area of one square centimeter and 

 the cells counted by means of an oil-immersion lens. By the use of 

 this " direct " method they showed that the number of body cells 

 in milk was much greater than had been supposed. They found 

 that, in centrifuged samples such as had been used by previous 

 investigators, a large and variable number of cells rose with the 

 cream and so did not appear in the sediment. They also found 



10 Ward, A. R., Henderson, M., and Haring, C. M. The numerical determination 



of leucocytes in milk. State Bd. Health Calif., 19 Biennial Rpt., 142-156, 1908. 



11 Harris, N. MacL. The relative importance of streptococci and leucocytes in 



milk. Jour. Inf. Dis., Supple. 3, 50-62, 1907. 



12 Russell, H. L., and Hoffmann, C. Leucocyte standards and the leucocyte content 



of milks from apparently healthy cows. Jour. Inf. Dis., Supple 3 : 63-75, 1907. 

 Idem. Distribution of cell elements in milk and their relation to sanitary stand- 

 ards. Wis. Agr Exp. Sta., 24 Ann. Rpt., 231-253, 1937. 



13 Bergey, D. H. The leucoctye and streptococcus content of cows' milk. Univ. 



Penn. Med. Bui., 20 : 103-109, 1907. 



14 Kendall, A. I. The significance and microscopical determination of the cellular 



contents of milk. Coll. Stud. Res. Lab. Dept. Health N. Y. City, 3 : 169-181, 

 1907. 



15 Pennington, M. E., and Roberts, E L. The significance of leucocytes and streptoc- 



occi in the production Qf a high-grade milk. Jour. Inf. Dis., 5 : 72-84, 1908. 

 18 Miller, W. W. The significance of leucocytes and streptococci in milk. U. S. 

 Pub. Health and Mar. Hos. Serv., Bui. 56 : 491-498, 1912 (Reprint from Bui. 

 41, 1908). 



17 Stone, B. H., and Sprague, L. P. Some studies of the physiological leucocyte 



content of cows' milk. Jour. Med. Res., 20 (N. S. IS) : 235-243, 1909. 



18 Campbell, H. C. Leucocytes in milk. U. S. Dept. Agr., Bur. An. Ind., Bui. 



117:1-19, 1909. 



19 Hastings, E. G., Hammer, B W., and Hoffmann, C. Studies on the bacterial 



and leucocyte content of milk. Wis. Agr. Exp. Sta., Res. Bui. 6 : 189-218, 1909. 



20 Jordan, J. 0. Protection of public milk supplies from specimens contaminated 



with pus organisms. Amer. Jour. Pub. Hyg., 19 (N. S. 5) : 126-134, 1909; 

 20 (N. S. 6): 601-604, 1910. 



21 Heinemann, P. G., Luckhardt, A. B., and Hicks, A. C. On the production of 



sanitary milk. Jour. Inf. Dis., 7 : 47-66, 1910. 



22 Lewis, D. M. Practical municipal milk examinations. Jour. Amer. Pub. Health 



Assn., I : 778-782, 1911. 



23 Ross, H. E. The cell content of milk. Cornell Agr. Exp. Sta., Bui. 303 : 775- 

 ^ 793, 1911. Idem. Jour. Inf. Dis., 10 : 7-16, 1912. 



24 Scannell, J. J. Some practical considerations on the presence of leucocytes and 



streptococci in milk. Amer. Jour. Pub. Health, 2 : 962-970, 1912. 



25 Prescott, S. C, and Breed, R. S. The determination of the number of body cells 



in milk by a direct method. Jour. Inf. Dis., 7 : 632-640, 1911. 



