HARBISON, DECEMBEIt, IDOO. 49 



inserting a pin in either of these cells the same ropy mass may bo 

 drawn out. If an examination is made of the juices of the larva? at 

 diiTercnt stages of the disease the bacilli may be seen. Spores form 

 only after the death of the larvrc. The ropy decaying mass as well 

 as the scales contain large numbers of these spores. 



Weighing these facts it seems quite probable that Harrison was 

 working with but one disease, American foul brood. In his exami- 

 nation of the ovaries of queens taken from foul-brood apiaries, 

 Harrison reports the finding of bacilli in three queens. He reports 

 that he found bacilli in a larger number of eggs laid in an affected 

 colony, and writes : 



In view of these facts, I am of the opinion that the eggs of bees from diseased hires 

 may in some instances be infected. 



Harrison did not find Bacillus dlvei in any case of chilled brood 

 which he had examined and states that Mackenzie performed several 

 experiments with chilled brood and never found this organism in 

 any case where the brood had not been inoculated experimentally. 

 Harrison writes as follows concerning the distribution of the disease: 



I have examined diseased larvae from Canada, from Europe (France, Switzerland, 

 Austria, Germany, Italy and England), Cuba, and 13 States of the Union, ranging 

 from New York to California and from Michigan to Florida, and have succeeded in 

 isolating B. alvex from all of them. It is true that some of the cultures show certain 

 differences, but they have not been sufficiently pronounced to constitute even a well 

 marked variety of the species. 



Harrison may have isolated BaciUus alvei in hmited numbers from 

 material received from all these sources, but from his description of 

 Bacillus alvei one can not be sure that he always identified his culture 

 correctly. 



It may be well at this point to consider Harrison's description of 

 the organism which he identified as Bacillus alvei. In an abridged 

 form it is as follows: 



Occurrence. — Found in larvae of bees suffering from a disease known 

 as foul brood. 



Gelatin plates. — ^The appearance of the growth depends upon the 

 age of the colonies and character of the medium. In 24-36 hours 

 at 22° C. the colonies are observed to be small, oval, or lozenge- 

 shaped, bearing pecuUar shoots extending frequently from one end 

 and giving it a pear-shaped appearance. At the end of 48 hours the 

 colonies are larger, with fine projections shooting out in all directions 

 and forming circles. Later this appearance is destroyed by the 

 hquefaction of the gelatin. 



Agar plates. — In 12 hours at 37° C. the colonies are small and burr- 

 like. Further, concerning the growth on agar, he writes: 



On agar plates streaked with a light inoculation, most beautiful forms occur. The 

 growth of the bacilli spreads o\'er the surface and branches repeatedly, giviug the 

 13140°— Bull. 98—12 i 



