102 Report of the Department of Bacteriology of the 



cows which were most frequently tested in the Station herd, shows 

 that the germs were more numerous in the back quarters in 68 

 per ct. of the 213 sets of samples. The number of these sets of 

 samples varied with the different cows from 13 to 26. Sets in 

 which the germ content was more numerous in the back quarters 

 predominated in the case of 9 of the 11 cows. The cases in 

 which the larger germ contents were found in the front quarters 

 were largely confined to the early part of the lactation period 

 or to cases where a front quarter contained large numbers of a 

 particular germ which was practically absent from the correspond- 

 ing back quarters. 



The cause and significance of this unequal distribution of 

 germ life in the front and back quarters of the udder is unknown 

 but the fact is evident from any point of view from which the 

 data has been considered. 



Relation of bacterial count to period of lactation. — In search- 

 ing for the influences which keep the bacteria in the udder within 

 the comparatively narrow bounds which are shown by the pre- 

 ceding data, it will be of interest to observe the relation of the 

 germ content to the period of lactation of the animal. The data 

 were not complete with regard to the period of lactation in a few 

 cases but the results from 1,119 samples are given in Table VII. 



Table VII.— Bacteria in Udder at Various Months of Lactation. 



An examination of the above table shows that, with the ex- 

 ception of the two extremes of the table, there is no evidence of 

 any well marked connection between this germ content and the 

 period of lactation. It will be observed that the samples obtained 



