SACBROOD, A DISEASE OF BEES. 5 



with the resuh that sacbrood was produced in each. It might be 

 mentioned here also that other experiments made indicate that the 

 virus is killed by the application of a comparatively small amount 

 of heat. 



In 11 colonies, therefore, sacbrood has been produced experiment- 

 ally by feeding to healthy colonies the virus of this disease. In 8 

 of the 11 colonies the disease was produced by virus that had passed 

 through the Berkefeld filter. The disease, therefore, which bee 

 keepers have for a long time recognized as being different from either 

 American or European foul brood has now been demonstrated to be 

 an infectious disease that is caused by a filterable virus. 



The conclusion to be drawn from this work, therefore, is that 

 sacbrood is an infectious disease of the brood of bees caused by an 

 infecting agent that is so small, or of such a nature, that it will 

 pass through the pores of a Berkefeld filter. 



The three principal brood diseases, then, are now all known to 

 be infectious. These diseases are: American foul brood, caused by 

 Bacillus larvae; European foul brood, caused by Bacillus pluton ; 

 and sacbrood, caused by a filterable virus. 



Approved : 



James Wilson, 



Secretary of Agriculture. 



Washington, D. C, December 10^ 1912. 



ADDITIONAL COPIES o f this publication 

 -t\. may be procured from the Superintend- 

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 OflBce, Washington , D. C. , at 5 cents per copy 



