80 STATE BOARD OF AGRICULTURE. 



2. Yeasts. 



Cultivated yeasts: Beer yeast. Bread yeast. Wine yeast. Milk yeast. 

 Wild yeasts: Torulae from pickles, from butter, from air, from milk, 

 from ensilage. Photographs, clay models, microscope with Hansen 

 chamber. 



3. Bacteria. 



Arranged in biological groups. 



Dairy bacteria, in litmus milk. Soil bacteria on potato. Water and sew- 

 age bacteria on broth. Pigment bacteria on agar. Disease bacteria on 

 bfood serum. Photogenic bacteria (in the dark room). 



Microphotographs of bacteria. Flagella. Spores. Microscopes with 

 Bacillus subtilis, Sarcina lutea. Spirillum riihrum, B. prodigiosus 

 (flagella stain). Spore contrast stain. Clay models. 



4. Protozoa. 



Cultures in hay infusion. 



Microscopes with Paramecium from soil, living, and with Sarcosporidium . 

 in tissue (stained). Photographs. 



b. bacteriology op domestic science. 



1. Preservation and Deterioration of Foods. 



Foods can be made to keep either by killing the micro;>rganisms which decom- 

 pose them, or by preventing them from growing and multiplying. Bacteria 

 are usually killed by heat or antiseptics. Growth is prevented by low tem- 

 peratures (cold storage), drying, concentrating. 



1. Heating. 



Sterilization by one heating. — Fruit preserves, jelly. 



Sterilization by one heating under pressure (generally used in the can- 

 ning industry).— Tin cans with vegetables and fruit. Spoiled preserves, 

 due to some bacteria very resistant to heat. Pure cultures and photo- 

 graphs of such bacteria. Milk, 6 months old. Different fruit jars and 

 covers in common use. 



Sterilization by intermittent heating.— Recommended for home canning 

 of vegetables, heating on three successive days for about one hour each 

 day. Specimens of students' experiments, one year old. Sterile milk. 

 Wash boiler which may be used for home canning. 



Pasteurization. — Commonly used for milk, because it does not affect the 

 taste. It is accomplished by heating 20 minutes to at least 160°F. 

 (60°C.) and cooling rapidly. Disease germs are killed and the others, 

 decomposing the milk, are greatly reduced. Pasteurized milk does not 

 keep much longer than unheated milk. Pasteurized cider, 6 years old. 



2. Drying, Evoporating, Condensing. 



Meat (Dried beef, meat extract). Vegetables. Apples, dates, apricots, 

 raisins, prunes. Milk (Condensed, evaporated, powdered). Cheese 

 (Sapsago). Eggs, dried whites for clarifying soups, coffee, etc. Malt 

 extract. 



3. Salting. 



Brined cucumber pickles. Common household method. Prevention of 



scum growth by sealing the pickles air tight with oil. Pure culture 



of scum yeast. 

 Salted meats and fish (dry and brined). Dried cod. Corned beef. Eggs 



preserved in salt brine. Salted butter. 

 Scums and pure cultures of brined pickles, olives, dill pickles, brined 



meat and fish. 



4. Sugaring and Preserving. 



Jellies, preserves and marmalades, inoculated, with and without paraffin 

 on the surface. Candied fruits — plums, pine-apple, cherries, etc. 



5. Oil. 

 Sardines. 



6. Chemical Preservatives. 



Boric acid. Salicylic acid. Benzoate of soda (1 gr. weighed out and 

 placed beside 100 cc. of ketchup). Saltpeter for meats (1 oz. to 25 

 lbs. of beef). Formalin in milk (.05%). Hydrogen peroxide in milk 

 (.5%). Ethyl alcohol. Eggs preserved in water-glass. 



