Apr. 12,1924 
Development of American Foulbrood 
151 
action, or Bacillus larvae itself may have the ability to produce enzymes which 
hydrolyze the glycogen, or it may be a combination of both. Through the 
utilization of this reducing sugar one would expect that there at least would be a 
considerable production of acid, but, as stated earlier, the hydrogen-ion concen¬ 
tration of dead ropy material is never found to vary much from Ph— 6.6 to 6.8. 
Since the data available concerning the biochemical reactions of Bacillus larvae 
offer no explanation of this hydrogen-ion concentration, a series of experiments 
was devised, the results of which add materially to the knowledge concerning 
the biochemical reactions and relationships of Bacillus larvae. In certain 
cases where, because of the limitations on growth, cultural growth has failed, 
it was found possible to obtain the desired information by examination of the 
diseased larval remains. 
UTILIZATION OF GLYCOGEN 
According to Straus (Table IV, fig. 15) the greatest percentage of stored 
glycogen occurs just after sealing, when feeding has ceased. If an emulsion of 
the tissues of a larva of this age, or slightly older, at the age when prepupse usu¬ 
ally die of American foulbrood, is tested for the presence of glycogen with iodin 
solution, 4 the resulting deep reddish brown color shows that there are large 
a.mounts of glycogen present. If a prepupa which has just died from disease, 
slimy in consistency, light brown in color, and which in the microscopic picture 
still shows the presence of vegetative rods, is tested with iodin solution, it will 
4 Glycogen treated with iodin solution gives a color varying from brown to wine red, which disappears 
upon heating to 60° C., but returns again upon cooling. Soluble plant starch with iodin solution gives 
the following reactions: Amylodextrin, first dextrin of conversion, dark blue; erythrodextrin, second dex¬ 
trin of conversion, red; intermediate steps give various shades of purple or lavender. 
