EXPERIMENT STATION REPORTS. 195 



Perhaps arrangements could be made with the bacteriologist doing the Avork 

 for the neighboring city of Ann Arbor. 



We suggest that all milk dealers selling in the city be required to have 

 steam in their plant, and that some of the poorer plants be gradually 

 eiminated. 



AVe would also suggest that the indiscriminate use of the term "Grade A" 

 be forbidden. A case was found where this term was applied to milk of 

 doubtful quality. [L. H. Cooledge.] 



Mr. Huddleson has made progress on his project, Adams 3b, probably 

 aided by the fact that he is able to devote his undivided attention to his in- 

 vestigations. We have a considerable investment in the equipment and ex- 

 perimental animals and it would be in the interest of economy to provide 

 more men to make greater use of these facilities with the object of bringing 

 results more quickly and more far reaching in their scope. 



REPORT OF RESEARCH ASSOCIATE I. F. HUDDLESON 



During the past year my time has been devoted entirely to the problcn in 

 bovine infectious abortion. 



The following problems have been reported on during the past year: 



The Susceptibility of Swine to Infectious Abortion, Bad. Abortus (Bang). 

 Vide, Quarterly Bulletin, Michigan Agricultural Experiment Station, No- 

 vember, 1921, p. 43. 



The Comparative Pathogenicity of Several Strains of Bad. Abortus (Bang). 

 Technical Bulletin No. 55, Michigan Agricultural Experiment Station, 1922. 



During the past year an attempt has been made to extend the immuniza- 

 tion studies into several badly infected herds in Michigan. The treatment, 

 when possible, was carried out under my personal supervision. Up to the 

 present time (June, 1922,) 23 herds representing 360 head of cattle have 

 received the vaccine treatment. Sufficient time has not yet elapsed to per- 

 mit of a report on the results of the treatment. 



We have in the experimental herd at the present time 33 heifers and cows, 

 and 2 bulls, of which 16 cows belong to the Michigan State Department of 

 Agriculture. These animals were obtained through the kindness of Mr. H. H. 

 Halladay, then Commissioner of Agriculture, from the Coldwater State 

 School. 



We now have at the experimental barn 10 virgin sows and 1 boar which 

 are being employed in studying porcine abortion. 



The following problems are now being studied : 



1. Diagnosis of bovine infectious abortion. 



(a) by means of serologic tests. 



(b) by means of allergic reactions. 



2. The persistence of Bad. abortus in the tissues of an infected animal. 



3. Immunization. — Under this general heading come the following prob- 

 lems : 



(a) The duration of the immunity. 



