120 Report of the Department of Bacteriology of the 



Dairy Expert at the Station, who has courteously placed the records 

 of the Station herd at the author's disposal. The completeness of 

 these records adds greatly to the value of the work. Mr. J. K. Wilson, 

 former Assistant Bacteriologist at the Station, Mr. G. L. Ruehle, 

 Assistant Bacteriologist at the Station, and Mr. I. R. Stidger and 

 Mr. F. C. First, former Assistants in Biology at Allegheny College, 

 have all helped in the work. Credit is given to them for this help 

 in the body of the paper. 



PRESENT STATUS OF THE QUESTION OF THE HYGIENIC 

 SIGNIFICANCE OF THE BODY CELLS IN MILK. 



It has long been known that many of the secretions of the 

 human body contain cells discharged from the tissues of the body, 

 and that these cells are in general of two kinds : (a) Epithelial cells 

 discharged either from the secreting portions of the glands or from 

 the lining of ducts or general epithelial surfaces, and (b) leucocytes 

 which make their way through the walls of the capillaries and the 

 lymphatics into the epithelial layers which form the secretion of the 

 gland and thus, finally, into the secretion itself. Under certain 

 pathological conditions the discharge of these cells may increase 

 greatly above the normal amount. 



Under normal conditions, the secretion of the sebaceous glands, 

 which lie at the roots of the hairs of mammals, is entirely composed 

 of disorganized cells which in this case are of an epithelial nature. 

 The saliva in the mouth commonly contains leucocytes together 

 with numerous cells discharged from the epithelial lining of the 

 mouth and the salivary glands. Cellular debris from a variety of 

 sources occurs in urine under normal conditions. 



It has likewise been known since 1837 2 that colostral milk con- 

 tains certain cellular bodies called colostral corpuscles. These 

 corpuscles have usually been regarded as detached epithelial cells, 

 although some have claimed them to be leucocytic in nature. It 

 is ordinarily stated that these colostral corpuscles disappear from 

 the milk within a few days. 



During the period from 1837 to 1900 and later, numerous investi- 

 gators studied the histology of the mammary gland and the processes 

 of milk secretion. Many of these investigators found that cells 



8 Donne\ A. Du lait et en particulier de celui des nourrices. Paris, 1837. 



