THE CELLULAR CONTENT OF MILK 131 



It has also been shown by numerous observers that the cell 

 count is greatly increased when the milk is raised before centri- 

 fugalising, to a temperature of about 70 C. It is believed that this 

 preliminary heating destroys some of the agglutinating properties 

 known to occur in milk, and that in some way it modifies the fat 

 globules, rendering them unable to entangle and carry up the cells. 



In relation to the fallacies apparently shown when milk is 

 centrifugalised or is not heated before the estimations are made, 

 it is contended that the percentage loss is probably approximately 

 equal in all the samples examined. In considering the cellular 

 content of milk from an individual cow, although the absolute 

 content may not be accurately estimated, yet the differences will 

 remain the same in all the estimations : thus any marked rise in 

 cellular content would, it is believed, be readily noted although the 

 absolute number might not be obtained. 



In view of the defects in the methods which have been employed, 

 it seems probable that many of the recorded cell-counts in milk 

 are not accurate. There seems, moreover, little doubt that the 

 differences between the cellular content of the milk of individual 

 healthy cows is greater than the inaccuracies which may reason- 

 ably be attributed to the methods used. It would seem impossible 

 to fix any figure as the normal cellular content of milk ; the varia- 

 tions found are too great. 



The attention of most observers has been directed towards 

 determining at what figure the cell count could be considered to 

 be abnormally large, and whether such an abnormal count could 

 be directly associated with diseased conditions of the cow or of 

 the udder. It appears that no such direct association can be 

 found, and that the cell count frequently fluctuates from day to 

 day between figures which might be regarded as either normal or 

 abnormal. No factors have been found to account for such change 

 in many of the instances. 



If disease were present it is probable that a high cell count 

 would be accompanied by other changes. It has been shown 

 already, in dealing with the presence in milk of ferments and of 

 immune substances, that the content of these rises appreciably 

 in early inflammatory disease of the udder. Several observers 

 claim to have established a connection between an increased cell 

 content and the presence of an undue number of bacteria, chiefly 

 streptococci, in milk. Observations connecting the ferment 

 content and the immune substance content with that of strepto- 

 cocci or other organisms, and also with the high cell content in the 

 milk, do not appear to have been made. It would seem, however, 

 that there is sufficient evidence of the connection between a high 

 cell content and the presence of a large number of streptococci 

 to render further examination advisable, if the cell count should 

 reach a figure which may reasonably be regarded as abnormal. 



A method of estimating leucocytes or white blood corpuscles 



K 2 



