CHAPTEE XI 



THE CELLULAR AND SEDIMENT EXAMINATION OF MILK 



The varieties of cellular elements in milk and the chief factors 

 influencing the numbers present have been considered in 

 Chapter I. The nature and volume of solid deposit obtained by 

 ceutrifugalisation or sedimentation of milk samples was also 

 described. The present chapter is concerned with three esti- 

 mations and their utility in practical milk examination. 

 They are the following : 



A. The numerical estimation of the cellular content. 



B. The examination of the stained centrifugalised deposit. 



C. The estimation of the volmne or weight of sediment 

 obtained from milk. 



A. Estimation of the Cellular Content 



Stokes and Wegefarth in 1897 first devised a method for 

 the enumeration of the cells, or, as they are usually called, 

 leucocytes in milk. Their method was based upon the number 

 of leucocytes per microscopic field of a preparation made by 

 centrifugalising 10 c.c. of milk, spreading the sediment on a 

 slide, and staining with methylene blue. Bergey, Stewart, 

 and Slack all used a very similar procedure. This method and 

 modifications of it are extremely inaccurate. Eussell and 

 Hoffmann found variations of 112 per cent as compared with 

 6 per cent using the Doane-Buckley procedure. 



Prescott and Breed ^ have recently modified the direct 

 counting procedure as follows. The sample is well shaken to 

 distribute the cream equally through the milk. A measured 

 drop (O'Ol c.c.) is then withdrawn by means of a specially 



1 Journ. of Inf. Diseases, 1910, vii. p. 6o2. 

 191 



