2 BULLETIN 517, U. S. DEPARTMENT OP AGRICULTURE. 



taniinated incubators or brooders could be controlled readily by sani- 

 tary meiisures, but infection through the egg must be prevented by 

 a process of weeding out the carriers among the hens used for 

 breeding. 



THE AGGLUTINATION TEST. 



Since the presence of the Bacterium pullorum in the ovary of the 

 hen is not betrayed b}^ external symptoms, it was necessary to devise 

 a biologic method of diagnosis in order to detect the presence of the 

 disease in the affected birds. The agglutination test was found to 

 be applicable for this purpose, and several agricultural experiment 

 stations have taken up the work on an extended scale, offering the 

 service to poultrymen at a price that barely covers the cost of the 

 work. This, in Connecticut, is understood to be 10 cents a fowl. 

 The work of drawing blood samples and sending to a laboratory is 

 necessarily tedious and relatively expensive as compared with the 

 value of a bird. A simpler, cheaper, and equally accurate diag- 

 nostic method would undoubtedly contribute to greater popularity 

 of this valuable work in disease prevention. 



EXPERIMENTAL WORK. 



The writers have undertaken to determine the possibility of pre- 

 paring a biological product from Bacterium pullorum to be used for 

 the diagnosis of the disease caused by that organism. The general 

 idea was to develop a diagnostic method somewhat analogous to the 

 intradermal tuberculin test, particularly as applied to fowls. 



TEST OF ARTIFICIALLY INFECTED BIRDS. 



Two strains of Bacterium jniUorum were planted in 1,500 c. c. of 

 plain bouillon in the amount of one loopful each. This culture was 

 incubated at 37° C. from September 19 to October 19, 1914. It was 

 then placed in the ice box until May 4, 1915. On this date 100 c. c. 

 of the culture was passed through a Berkefeld filter. The filtrate 

 Avas determined to be sterile by cultural tests. Carbolic acid was 

 then added in sufficient quantity to make a 0.5 per cent solution. 



On May 17, 1915, two drops of this filtrate were injected into the 

 light wattle of a hen that had been injected with Bacterium pullorum, 

 on September 22, 1914. The liquid was injected slightly above the 

 lower border of the wattle and no attempt was made to place it 

 within the layers of skin. Twenty-four hours later the wattle showed 

 :ui edematous swelling. The following day, 48 hours after injection, 

 there was noted a pronounced edematous infiltration of the entire 

 wattle. A swelling of this size in other intradermal tests would be 

 considered as positive. The temperature was normal. On May 20 

 the swelling of the wattle decreased (•< nsiderably, and 90 hours after 



