900 Popular Editions of Station Bulletins of the 



This new method of determining the bacterial 

 Why and content of milk, by the use of the compound micro- 

 where use scope to count the organisms in stained milk smears 

 the new on glass slides, from its rapidity, inexpensiveness, 

 method? simplicity, absence of delicate manipulations calling 

 for high technical skill, and wide scope in identi- 

 fication, seems a very promising assistant in the examination of milk. 

 It is hoped that this method, or some modification of it, can be 

 made of practical use to the milk dealer, butter-maker and cheese- 

 maker as a means of grading milk according to its bacterial condition. 

 This should make it easier for the farmer to secure a better price 

 for a high-grade milk than for a. poorer grade. 



CELLS IN MILK. 



It has been known for three-quarters of a century 

 Presence that the first milk of each lactation period, the 

 of cells in colostrum, contains cells derived from the udder or, 

 milk not through it, from the blood. The belief was, how- 

 new fact. ever, that these cells soon cease to be discharged, 

 and that few are present in normal milk. 

 Recent studies, though, especially those made during the past 

 fifteen years, have proved that cells in large numbers are found in 

 all normal milk; and that in some cases, which have accordingly 

 been considered abnormal or the result of udder infection or disease, 

 the multitude of such bodies seen under the compound microscope 

 has been so great as to be almost beyond count. 



Much attention has been given to the development 

 Methods of methods for making such studies; but many of 

 of study. those employed have been indirect and complex. 

 Most of these methods have required the rapid whirl- 

 ing of the milk in a centrifuge to throw out the sediment; and the 

 samples for microscopic examination were taken from this sediment 

 — not from the milk itself. The new method of Prescott and Breed, 

 however, proves that not all of the cells in the milk are collected 

 in this centrifuge sediment; for the counts of cells made by this 

 method are much larger than those made by any examination of 

 samples from sediment. The new method is a direct one, as small 

 samples of the milk itself are taken and the counts made from 

 " smears " viewed under the microscope. Though devised for the 

 study of cell content of milk, this dried-smear method appears to be 

 of even greater value in bacteriological work, as already pointed out. 

 Cells in milk have been held by many students to 

 Why study be abnormal constituents and therefore undesirable, 

 cells? The makers of milk clarifiers have counted as one 



of the valuable features of clarification the fact that 

 this process removes many cells from the milk. 



