EXPERIMENT STATION REPORTS. 251 



The aggliitiuatiou test is of value in studying the presence of Bad. 

 aboi-tus in milk when it is desired to study a large number of samples. 



If Bact. 'ahortus is found to be pathogenic for humans, this test may 

 be of value as another means of safeguarding certified and all unpas- 

 turized milk. 



We have no conclusive evidence that Bact. ahortus is pathogenic for 

 human beings, but it is possible to cause antibodies for Bact. ahortus to 

 appear in the blood of adults by feeding a milk which is naturally in- 

 fected with Bact. ahortus and wliich contains the Bact. ahortus anti- 

 bodies. 



Antibodies appearing as above apparently indicate a passive immunity 

 due to the absorption in the large intestine of the antibodies present in 

 the milk. 



Mr. I. F. Huddleson has been working on the transmission of Bact. 

 ahortus through the milk touching upon the following points: 



(1) The effect on rabbits, guinea pigs and calves respectively of feed- 

 ing naturally and artificially infected milk. 



(2) The significance of the matting of the hairy tufts about the or- 

 ifice of the sheath and at the lower commissure of the vulva of calves. 



While much of my time during the past year has been occupied in 

 studying the subjects taken up in the above lists. I have kept in mind 

 other branches of my general problems and have gathered data for dif- 

 ferent phases of this work. (L. H. Cooledge). 



Mr. Cooledge submits the following report on investigations having in 

 view the establishment of a proper basis for educational, extentional ef- 

 forts in connection with the production and marketing of a clean and 

 safe milk supply. 



MARKET MILK CONTESTS AND DAIRY SURVEYS. 



During the past few years many investigations have been carried on 

 upon the effect of the presence of certain types of bacteria upon the milk. 

 Some types have been found undesirable because they are pathogenic, 

 others because of undesirable fermentations which thev cause, while 

 others are undesirable because their presence indicated that the milk 

 has not been handled in a hygienic manner. 



To keep undesirable types of organisms out of milk requires a good 

 deal of care at every step in the production and handling. Obviously edu- 

 cational campaigns must be carried on among the producers and con- 

 sumers of milk to show the value of certain sanitary practices. 

 During the past year a study has been made of some of the methods used 

 ill stimulating interest in a pure milk su]>])ly. This study has been 

 aluiig the following lines: 



Market milk contests. 



Market cream contests. 



Sanitar}' survey of milk plants. 



Sanitary survey of dairy farms. 



Sanitary survey of milk-plant water supplies. 



As a result of these contests and surveys the writer is of the opinion 

 that an occasional contest or sanitary survey carried on in the right 



