168 IOWA ACADEMY OF SCIENCES. 



It does not depend upon the use of a particular kind of flour, 

 as a number of brands were used where the condition was 

 present. In all the cases which came to my notice there was 

 one condition uniform; viz, the bread had been kept at a com- 

 paratively warm temperature after baking. In no case was 

 the trouble found to occar where the bread was kept in a cel- 

 lar or other cool place. 



THE RELATION OF HEAT. 



To test the effect of heat, a loaf was taken from a baking of 

 good quality and cut into halves. One half was placed in an 

 incubator at a temperature of about 95^ Fahrenheit, the 

 other in a cool basement with a temperature of about 60"^ 

 Fahrenheit. Within three days the piece in the incubator 

 showed the' typical condition of the fermentation, while 

 the piece in the cool basement showed no change, even 

 after two weeks. A sample was also secured during the 

 month of November from two families who had been 

 troubled during the joi'eceding summer, but at this time 

 the bread appeared to be normal in every respect. This 

 bread placed at 95° Fahrenheit became stringy within two 

 days. Samples were later secured from a number of families 

 in the habit of making their own bread, also from one 

 bakery. The samples were placed in Petri dishes, moistened 

 with distilled water, then heated in the Arnold sterilizer for 

 thirty minutes to destroy any bacteria that might be present 

 by accidental contamination. The bacteria which produce 

 the condition being able to withs.and the heat of baking, could 

 survive this temperature, which is about the same. After the 

 heating, the samples were put at a temperature of 95^^ Fahren- 

 heit. In every case where cake yeast had been used, the 

 stricgy condition appeared in the bread. The bread from the 

 bakery had been fermeated with compressed yeast and this 

 bread showed no change whatever when kept at the warm tem- 

 perature. Examination of this yeast, as noted later, showed 

 it was free from the obnoxious bacteria. A sample from a 

 baking of home make bread, fermented with this same com- 

 pressed yeast was the only home-made bread tested which did 

 not undergo the stringy decomposition when placed at a high 

 temperature. 



From these observations we may conclude that a large 

 amount of bread contains the spores of this fermentation and 



