47 



ill basements, in "sweatshops," and by people who were not snrticieiitly clean, 

 personally, have been dwelt upon in newspapers, and even in the ('entuiv Maga- 

 zine an article appeared a year or so ago from a prominent member of the New 

 York Board of Health, advocating certain methods of making bread in which 

 baking powder should be used instead of yeast, so as to do away with the kneading 

 and the consequent handling of the dough. Some of the cooking school teachers 

 have advocated the same thing, claiming in addition that in bread not thoroughly 

 cooked the yeast is not killed, and that on its introduction into the stomach a 

 fermentation is set up. 



To test the validity of these claims I made a number of experiments upon 

 breads gotten from Lafayette bakers, the brcails being obtained from the grocers 

 the object for which they were to be used not being stated. Specimens of the 

 ordinary loaves, and also rolls that require a shorter time in baking, were ob- 

 tained, an attempt being made also to select those specimens showing the least 

 baking. In making the tests care was taken that outside germs should not be in- 

 troduced. I first washed my hands with corrosive sublimate solution, then 

 singed the outside of the loaf by means of a gas flame; the loaf was then broken 

 open and a piece of about one gram weight taken from the center with sterilized 

 forceps and placed in test tubes of sterilized beer wort. The specimens of bread 

 were allowed to remain in this medium for about ten days, then plate cultures 

 were made, the gelatine for the plate cultures being inoculated from the wort in 

 the tubes. Duplicate experiments were made of each specimen of bread used. 



Beer wort is one of the best media for the cultivation of yeast, as it contains an 

 abundance of the food necessary for its growth. It is also valuable as a medium, 

 as it becomes turbid by the growth and froths readily in the fermentation. 



In the experiments in no case was there any apparent growth in the wort; it 

 remained perfectly clear, and no gas was formed. In the plate cultures no 

 growth took place, except in one case in which a mould grew. It is' very probable 

 this was introduced in the manipulation, as the duplicate showed no growth. 



Duplicates of these experiments were made with bread obtained from Boston, 

 with the same results. The Boston bread was bought in some of the large grocery 

 stores and restaurants, which would, of course, insure the bread having come 

 from reputable bakers. I was not successful in obtaining any basement made 

 bread or that from so-called "sweat-shops" where the cleanliness is questionable. 



Enough has been done, however, to demonstrate that yeast and the oriiinarv 

 bacteria found in dough are killed in the baking, and that any germs introduced 

 into the stomach by means of the bread have come from the outside of the loaf, 

 and have been deposited upon it after the baking. If any doubt exists in one's 

 mind in regard to the place from which lie has olitained bread, it is very easy to 



