DEPARTMENT REPORTS. 81 



7. Smoking. 



Smoked meat. Ham, bacon. 

 Sm.oke(i fish. Halibut, herring. 

 Coal tar products. Creosote. 



8. Spices. 



Fruit cake. Mince-meat. Ketchups of various sources — some with molds 

 and some fermenting. Oil of cloves, cinnamon, allspice, mustard. 



9. Peeseevation by Fermentation. 



Preservation is secured through the production of large amounts of acid 

 which prevents undesirable bacterial growth. Sauerkraut, brine pickles, 

 dill pickles, fruit juices, sour cream butter, cheese. Fresh meat pre- 

 served temporarily in buttermilk and in vinegar. Pure cultures from 

 sauerkraut, vinegar and milk scums. 



TJ. Bread. 



1. Salt-rising Bread. 



Salt-rising bread is risen by a bacterium (Bacterium aerogenes) which 

 produces large quantities of gas. Pure culture of germ under the micro- 

 scope, in milk and on agar. Gas production in fermentation tube. Sam- 

 ples of corn meal, canaille and sweet milk where Bad. aerogenes is 

 ordinarily found. Exhibit two loaves of bread; one made at bakery, one 

 made in the laboratory from a pure culture of the germ. 



2. Yeast Bread. 



Fleischmann's compressed yeast cake. Magic yeast cake. (Demonstrate 

 colonies from a oake 4 years old, still alive.) Slimy, moldy and pig- 

 mented breads. 



III. Vinegar, 



stains of acetic bacterium and yeast involved in the manufacture of vinegar. 



Yeast grown in sterilized cider showing alcoholic fermentation (hard cider). 



Acetic bacterium in sterile cider without yeast. Yeast and acetic bacterium 



grown together producing vinegar. 

 Commercial culture for vinegar production. 

 Cider vinegar, tomato vinegar. Impure vinegar. Vinegar eels. 

 Quick vinegar process. 



C. DAIRY BACTERIOLOGY. 



I. Milk. 



1. Bacteria in Milk. 



Market milk — plates from fresh sample. Certified milk — plates from fresh 

 sample. Bacteria from udder of cow — plates from fore-milk, middle 

 milk, and strippings. Effect of straining upon number of bacteria — 

 plates made before and after straining, show strainer. Effect of separa- 

 tion upon numbers — plates from cream, milk, and separator slime. 

 Microscope — stain from market milk showing cells and bacteria. Pure 

 cultures in litmus milk of a number of different milk microorganisms. 



2. Contamination of Mtlk. 



Tubes of sterile milk, to which has been added a piece of sterile straw, 

 of sterile hay and some sterile soil. To which has been added straw, 

 hay, litter from barn fioor, cow's hair, soil, etc. 



Plates showing number of microorganisms in barn air (before and after 

 feeding), in laboratory air, in clean milk bottle (before and after steam- 

 ing), in poorly cleaned milk utensils, as pails, strainers, separators, etc., 

 and on hands (before and after washing). 



3. Constituents of Milk, Butter and Cheese. 



Samples of the different constituents and table showing percentages. 



Action of microorganisms upon casein — shown by milk agar plates and 

 milk cultures. 



Action upon lactose — acid in litmus milk and carbonate lactose agar 

 plates; gas in fermentation tubes of whey, lactose agar tubes. 



Action upon butter fat — shown by comparison of growth of certain micro- 

 organisms upon synthetic agar and fat-synthetic agar plates. 



Microscope showing fat globules in whole milk. 

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