4 MASS. EXPERIMENT STATION BULLETIN 163. 



ing this infection. Gage ^ and Rettger ^ have also used and apphed it with 

 good results, both in diagnosing the infection and as a basis for control 

 and eradicating the infection from breeding flocks. 



Establishment of Methods for detecting Carriers of the Disease. 



Since it has been shown conclusively by the workers quoted above that 

 infected ovaries constitute the real source of infection in bacillary white 

 diarrhea of cliicks, the basis of prevention rests to a great extent upon 

 this significant fact. Then, too, the work already cited has exhibited the 

 scientific proof which shows that chicks surviving an attack of bacillary 

 white diarrhea may become permanent carriers. 



Attempts have been made to apply various tests for locating this infec- 

 tion in adult hens, but the macroscopic agglutination test, as noted above, 

 which is discussed later in tliis paper, has proven reliable and practical 

 for testing the blood of mature stock. The results reported in Bulletin 

 No. 148 of this station, together with those reported from Cornell and 

 Connecticut, demonstrate that the value of the macroscopic agglutination 

 test can no longer be doubted. It furnishes a practical method of diag- 

 nosing infection in adult hens. It is inexpensive and reliable, and up to 

 the present time nothing has occurred to detract from the merits of the 

 test. In the hands of properly qualified persons, and carried out under 

 observation of the laws of pathology, both from the standpoint of the 

 study of disease and eradication of disease, as indicated by our records 

 to date, it is fast proving to be more and more valuable as a means of 

 detecting birds which may be a source of infection to young day-old chicks. 



Therefore, with tliis consideration, nothing should stand in the way for 

 proper authorities to make it possible for the present workers in this field 

 to continue this important work and apply the test extensively throughout 

 Massachusetts, and aid in ridding breeding flocks throughout the State 

 of these permanent carriers of Bacterium puUvrum. Backed by our 

 present data from the laboratory, this work could be carried on with 

 every promise of success. 



Infection in Massachusetts. 



The establishment of such important facts in regard to bacillary white 

 diarrhea as its cause, original source, and mode of transmission, and the 

 perfection of a test which is able to detect the sources of the disease, are 

 subjects which have been referred to in an earlier part of this paper. The 

 question which confronts the poultryman of Massachusetts is, ''Does 

 baciUary white diarrhea exist to any extent in Massachusetts?" In reply 

 to this question we set forth the data that we have obtained up to date, 

 as well as the methods used in procuring them. 



1 Gage: "On the Diagnosis of Infection with Bacterium pullorum in the Domestic Fowl." 

 Massachusetts Agricultural Experiment Station, Bulletin No. 148, April, 1914. 



2 Rettger: Storrs Agricultural Experiment Station, Bulletin No. 77, June, 1914, p. 272. 



