l886.] NEW-VORK MICROSCOPICAL SOCIETY. 45 



•of the Saccharomyces as compared with that of the Bacillus. 

 The actions are different, as we may easily see by comparing 

 the taste of bread made with yeast with that of bread made 

 with leaven. Such difference is doubtless caused by products 

 of fermentation of variable nature and number. 



It is now possible to give a brief resume of the principal 

 phenomena that occur during the preparation of bread. 

 Through kneading, the dough acquires a homogeneous compo- 

 sition in every part. Upon contact with water and the soluble 

 ferments derived from the triturated cells, a portion of the starch 

 and albuminoids becomes more easily assimilable for living 

 beings. The organic ferments, Saccharomyces ox Bacillus, mixed 

 with the dough during kneading, feed on the substances that 

 have become soluble, and produce carbonic acid gas. This 

 latter accumulates in the cavities of the gluten, and thus, 

 through the intervention of these organisms, the bread acquires 

 lightness and savor. Baking finishes these modifications by 

 altering the structure of the starch grains that have remained 

 intact, and by increasing the size of the cavities through the ex- 

 pansion of the gas by heat. So the size of the loaf greatly 

 increases in the oven. The external surface of the dough under- 

 goes completer transformations than the central part does, in 

 consequence of the higher temperature to which it is submitted. 

 The starch is converted into dextrine, especially if there be a 

 little steam in the oven, or the surface of the loaf be moistened 

 with water ; and thus results the beautiful, golden varnish so 

 much liked by consumers. 



This study of Bacillus panificans will permit us to explain 

 the cause of 



Ropiness in Bread. — During the warmest months, from June 

 to September, it often happens that bread prepared in 

 country houses undergoes transformations of a peculiar na- 

 ture. Two or three days after being baked, it emits a putrid 

 odor, and, when eaten, has a saccharine and not unpleasant 

 taste. In a short time, the odor becomes stronger, and recalls 

 that of albuminoid substances in a state of decomposition, and 

 a finger inserted in the loaf shows the interior to be of a ropy 

 consistency. This state of the bread is caused by the Bacillus 

 panificans, when there is lack of sufficient acidity. The trouble 

 may be prevented by the addition of a sufficient quantity of 

 some organic acid to the dough. 



