lSTr.w York Agricultural Experiment Station. 121 



or cell fragments were present in the secretion of the gland as it 

 was first formed in the alveoli but few of them studied milk itself 

 to see whether the cells were discharged or not. Recent workers 

 among these histologists have nearly all recognized the dual nature 

 of the cells, the best statement of the modern view in regard to 

 them which has come to the attention of the author being found 

 in a new book by Ernst 2a received while the present paper was 

 in press. 



No particular attention had been attracted to the presence of cells 

 in milk itself until Stokes and Wegefarth 3 called attention to the 

 presence of leucocytes in market milk. They distinguished these from 

 the epithelial cells in the milk by the form of their nuclei. The 

 method which they used for obtaining the cells for examination was 

 to centrifuge a given quantity of milk from individual cows. A 

 practically constant amount of the slime thus secured was removed 

 by the use of a platinum loop and smeared on a slide, dried, stained, 

 and examined under an oil-immersion lens. When more than five 

 leucocytes per field were found, they considered the milk unfit for 

 use. Throughout their earlier papers, they speak of leucocytes as 

 " pus " cells, an unfortunate use of the word which has been kept 

 up by many writers. Leucocytes occur normally not only in blood 

 vessels and in lymphatic tissues and vessels, but also make their 

 way out of these into almost all of the other tissues of the body. 

 Thus their .mere presence in milk, even in large numbers, does not 

 justify the use of the term " pus " cell except where they are shown 

 to have the significance of pus cells. Attention was immediately 

 directed to the presence of the cells thus interpreted as "pus" cells 

 and other investigators took up the work of devising better methods 

 of counting them and of establishing definite numerical standards 

 by means of which normal milk could be distinguished from abnormal 

 milk. Both the method of counting the cells and the numerical 

 standard suggested by Stokes and Wegefarth have been shown to 

 have little value, but their work was of great importance because 

 it directed attention to the universal presence of cells in milk and 

 raised the question of their sanitary significance. 



2a Ernst Wilhelm. Grundriss der Milchhygiene filr Tierarzte. Stuttgart, 1913. 

 3 Stokes, W. R., and Wegefarth, A. The microscopic examination of milk. Med. 



Neivs, 71 : 45-48, 1897. Idem, Jour. State Med., 5:439, 1897. Idem. Ann. 



Rpt. Health Dept. Baltimore for 1897, pp. 105-111. 



