Apr. 11, 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 nei^er 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. 





s e 7 



/o // 



Fig. 15. — Per cent composition of worker larvas at different ages (Tables IV and V) 



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 prepupae usu- 

 ally die of American foulbrood, is tested for the presence of glycogen with iodin 

 solution,' the resulting deep reddish brown color shows that there are large 

 amounts of glycogen present. If a prepupa which has ]'ust died from disease, 

 sUmy 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 



* 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: Amylodeitrin, first dextrin of conversion, dark blue; erythrodextrin, second dex- 

 trin of conversion, red; intermediate steps give various shades of purple or lavender. 



