150 Report of the Department of Bacteriology of the 



After the third day the left hind quarter discharged a greater 

 number of cells than any of the other quarters. This was one of 

 the quarters which was distant from the lump in the udder above 

 mentioned. The count on March 10 is especially interesting, for 

 the strippings of the left hind quarter on this date gave the highest 

 cell count of any apparently normal milk thus far examined. When 

 viewed under the microscope, the milk was found to be simply filled 

 with cells. Yet the macroscopic appearance of the milk was such 

 that three trained laboratory men failed to detect which was the 

 cell-rich milk when a sample in a test tube was placed beside three 

 similar samples containing small numbers of cells. The milk from 

 this animal was used with that of the other cows. The taste of the 

 milk was entirely normal and caused the person who used it no 

 evil after-effects. 



A bacteriological examination of the milk of this cow was made 

 by Mr. Ruehle from March 11 to March 19. The principal purpose 

 of this work was to discover whether a relation exists between 

 the number of cells discharged and the total bacterial infection 

 as indicated by the number of bacteria discharged, and to discover 

 whether any streptococcic infection existed. 



The technique used was the same as that used by Harding and 

 Wilson in their studies on the udder flora (Technical Bulletin 

 No. 27). Samples of strippings from each quarter were drawn into 

 sterile test tubes at each milking, plated on lactose agar and incu- 

 bated for 5 to 6 days at room temperature (23 to 25 degrees C.) 

 and the colonies counted. The plates were then incubated for two 

 days longer at 37 degrees C. and recounted. The averages of the 

 numbers of bacteria per cubic centimeter for the sixteen tests when 

 incubated at the lower temperature were as follows: right front, 

 4; right hind, 75; left front, 2; left hind, 11; average of the four 

 quarters, 23. When the plates were incubated at 37 degrees C. 

 for two days longer, the counts rose to the following averages: 

 right front, 9; right hind, 191; left front, 340; left hind, 260; average 

 of four quarters, 175. 



The averages in all of these cases are low as compared to those 

 found for the udder by other investigators, so that it is evident 

 there was no excessive number of bacteria present. Table IX 

 shows the details in regard to the cell and bacterial counts so 

 far as they were made under comparable circumstances. This 



