650 



STATE BOARD OF AGRICULTURE. 



part of the paper we take advantage of this fact in making a study of 

 the prevalence of Bad. ahortiis infected ndders, the methods by which 

 the udders become infected, the permanence of the infection in the udder, 

 and other questions of a practical nature. 



It is possible that this test may be of help in detecting infected milk 

 in order that it may be eliminated as possibly one of the important 

 factors in the spread of the disease. 



Very little work has been done upon the possibility of this infection 

 being transmitted to the young througii the milk. Huddleson says in 

 this regard : "Tliat Bad. al}ortu>^ antibodies develop in calves as a re- 

 sult of ingesting naturally infected milk seems to us to be a demon- 

 strated fact, but the cause and significance of the appearance of the 

 antibodies cannot be explained until further development of the studies 

 on the calves. The antibodies may be due to an active infection, they 

 may be due to an active imraunit}^ or they may be due to a passive trans- 

 mission of the antibodies present in the milk." 



Schroeder states that Cotton and he have succeeded in causing the 

 abortion disease in guinea-pigs by feeding them seemingly normal milk 

 from apparently healthy cows that had become chronic carriers of the 

 abortion bacillus. 



McFadyean and Stockman consider the digestive tract one of the 

 means by which the abortion organism gains entrance to the bodies of 

 cows. 



In the studies tabulated in this part of the paper the agglutination 

 test is largely depended upon as it has been shown that the agglutina- 

 tion and complement fixation tests correspond so closely that the two 

 tests are not required when milk is used as a test substance. 



To get an idea of the prevalence of this form of Bad. a'bortus infected 

 udders a number of farms was visited and samples of fore milk taken 

 from each quarter of each cow. These were brought to the laboratory at 

 once and agglutination tests made. In some instances the samples 

 stood over night in the ice box. Experiments have shown that such 

 delay does not influence the results. The results of this study are given 

 in Table I. , , i ; : ; 



TABLE I.— SHOWING THE PREVALENCE OF BACT. ABORTUS INFECTED UDDERS 



IN HERDS STUDIED. 



The data tabulated in Table I show that this infection of the udder 

 is very common in this part of the state at least. The first five farms in 

 the table were selected at random for study and probably give a better 

 idea of existing conditions than the whole table. The farms F and G 



