170 IOWA ACADEMY OF SCIENCES. 



THE NATURE OF THE VISCID MATERIAL. 



The question whether the viscid material is a result of the 

 decomposition of the bread or a mucilaginous product of the 

 cells themselves, is one of interest. Both the potato bacillus 

 and B. Uodermos produce a very viscid growth on the surface 

 of potatoes. The latter also produces a similar gummy sub- 

 stance on the agar agar. The viscid condition of these 

 growths appears to be due to the formation of a mucilage- like 

 substance by the cell itself and the stringy condition of bread 

 seems to be the same. Microscopic examination of the threads 

 formed from the bread showed a linear arrangement of cells 

 with intervening spaces quite regular in size. Neither 

 Welch's glacial acetic acid method or Gram's method show 

 any capsule with either of these species. The B. Uodermos 

 shows a clear area around the cells when s.ained with carbol 

 fuchsin indicating the formation of a gelatinous substance in 

 the nature of a capsule. Both of these organisms decompose 

 the nitrogenous part of the bread, as is shown by the uniform 

 presence of ammonia in the fermented material. 



EFFECTS OF BACILLUS SUBTILIS. 



The presence of this species in one sample of bread and its 

 wide distribution, making it possible that it easily finds its 

 way into many samples of bread, led to an experiment with 

 the object of determiniog whether it has the power of produc- 

 ing a slimy decomposition. A culture taken originally from 

 hay was used. "When grown on sterile bread it produced a 

 slight yellow coloration with an odor somewhat resembling 

 that produced by the potato bacillus, but no stringiness was to 

 be noticed. 



HEAT OF BAKING. 



It is evident the bacteria causing the fermentation are able 

 to survive the heat of baking. In this connection two experi- 

 ments were made to determine what the temperature inside a 

 loaf of bread is during baking. A thermometer was inserted 

 in the top of a loaf of bread with the bulb ia the center. Just 

 as the bread was ready for removal from the oven the tem- 

 perature was taken at intervals until the reading sank to 150° 

 Fahrenheit. It was observed in both trials that the tempera- 

 ture of the bread raise! several degrees within five minutes 

 after being removed from the oven, then slowly declined. 

 This increase in temperature after removal from the oven was 



