1997.] THE AMERICAN BEE-KEEPER. 199 



dium which would be satisfactory in On microscopic examination of the 

 this respect. Such a medium has been decaying larvae dead from the dis- 

 discovered, and large amounts of the ease thus produced experimentally, the 

 culture suitable for experimental inoc- same large number of spores and rods 

 ulations have been obtained. This are seen as when samples are exam- 

 medium is prepared and used as fol- ined which are taken from an apiary 

 lows: Healthy bee larvae or young affected with American foul brood, 

 pupae are picked from the comb, From these dead larvae pure cultures 

 crushed, strained through cheese cloth, of Bacillus larvae were obtained from 

 diluted with 20 to 50 times their plates, using the new medium describ- 

 volume of water, filtered through or- ed above. These experiments show 

 dinary filter paper, and then passed that by the feeding method the disease 

 through an earthenware filter (the may be produced and that the conta- 

 Berkefeld filter is satisfactory) ,to re- gion is found in the scales. The sec- 

 move any bacteria which are present, ond experiment tends to indicate that 

 The sterile fikrate thus obtained may the cause of American foul brood as 

 be pipetted into tubes or flasks and found in the scale is not killed by heat 

 stored until needed. When Bacillus at 65 degrees C. applied for twenty 

 larvae is to be isolated, a tube of the minutes. 



ordinary agar of the laboratory is li- Up to the present time there is no 



quefied and cooled to 45 degrees or authentic record of this disease hav- 



50 degrees C. Then about 2 c.c of ing been produced by experimental 



the filtrate mentioned above is added inoculations of pure cultures, 



to it. A very small amount of the Knowing that by the feeding meth- 



decaying larvae affected with Ameri- od the disease may be produced, pure 



can foul brood is then added. The cultures of Bacillus larvae have been 



procedure from this point is as usual mixed with sterile sugar sirup and 



in making agar plate cultures; these fed to healthy colonies with the re- 



olates are afterward incubated. When suit that the disease appeared in the 



a large amount of culture is desired colonies within three weeks with sym- 



for experimental purposes it is con- toms identical with those produced by 



venient to use the ordinary agar me- feeding the scales of the disease. In 



dium in large test tubes to which has the ropy brown mass of the decaying 



been added, as above, about 2 c.c. of larvae in the disease which is produc- 



the sterile larvae filtrate. These agar ^^ experimentally by feeding pure 



tubes are then inclined and the sur- cultures of Bacillus larvae there are 



face of the congealed agar is inocu- found the same large number of 



lated. In no case should the larvae ^po^es and rods as when the disease 



or filtrate reach a high temperature. '^ produced by feeding the scales or 



The object, of course, is to obtain a ^^^" the disease is found in an apiary, 



medium which contains the food con- P"*"^ cultures of Bacillus larvae have 



stituents which are afforded the bac- ^^^" obtained from the larvae dead 



teria in the living larvae. ^'"^"^ the disease produced experi- 



Inoculation experiments have been mentally by feeding pure cultures of 



made by feeding to a healthy colony bacillus larvae. 



the scales from combs which had con- Some European investigators of 

 tained brood affected with American brood diseases omit the symptoms, so 

 foul brood. The result of the feeding that it is impossible to tell which 

 was that the colony became affected disease they are investigating. Their 

 ^^v disease, the symptoms of which descriptions of microorganisms also 

 were the same as those observed in ^''e entirely too brief. These facts 

 the apiary where American foul brood have led to much confusion, and they 

 is found. Like symptoms have been necessitate much additional work ort 

 ^-oduced by feeding scales which had the part of other investigators. They* 

 been put into ordinary meat bullion, have also added to the present con- 

 incubated for twenty-four hours, and fusion. From what can ' be gained 

 then heated to 65 degreess C. for from their papers, the author is in- 

 twenty minutes clined to believe that Burri has been 



