DEPARTMENT REPORTS. 79 



You are very cordially invited. 



DEMONSTRATION IN BACTERIOLOGY. 



Prepared by the Laboratory of Bacteriology and Hygiene, Michigan 

 Agricultural College. 



A. GENERAL MICROBIOLOGY, 



Modern Microhiology includes, besides bacteria, molds, yeasts, pro- 

 tozoa and invisible organisms. 



I. Tools op the Bacteriologist. 



Microscope, slides, coverglasses, platinum needles, burners, steam and hot-air 

 sterilizer, autoclave, incubator. Test tubes, flasks, petri dishes, wire basket, 

 water-bath. Media, raw materials and finished products. Stains and stain- 

 ing utensils. 



Special apparatus: Pasteur flasks, Freudenreich flasks, Koch flasks, Barlow's 

 viability flasks, fermentation tubes. 



II. How Microorganisms Grow. 



Cider, sterile and with Saccharomyces cerevisiae (bread yeast) at various 

 stages of growth. Same with a mold. (Penicillium) . Cider with yeast in 

 fermentation tube to determine the amount and kind of gas formed. 



Milk, sterile and with Torula, and Bacillus suMilis (both organisms from ran- 

 cid butter). 



Litmus milk, sterile and with Bacterium lactis acidi (which makes milk sour) 

 and with Bacillus mycoides, (a soil organism). 



Potato, sterile and with Sarcina lutea (from the air), and with Bacillus 

 mesentericus (from soil). 



Meat-broth, sterile and with Bacillus coli (from the intestine) and with Mucor 

 mold. 



Meat-gelatin, sterile, with Bacillus prodigiosus and with Streptococcus 

 pyogenes, (from pus). 



Gelatin plate in petri dish from hard elder. 



Meat-agar, sterile and with Bacillus fluorescens (from water) and with 

 Staphylococcus pyogenes albus (from pus). 



Agar-plates in petri dishes from street dust. 



Blood-serum,, sterile and with Bacillus typhosus (the typhoid fever bacillus). 



III. Counting op Bacteria. 



Apparatus for direct counting of blood corpuscles under microscope demon- 

 strated with yeast. 

 Dilution flasks, sterile pipettes, counting plates. 

 Plates from 1/100 cc, 1/1,000 cc. and 1/10,000 cc. of dairy milk. 

 Plates from 1/100,000 cc. of good soil. 



IV. Pure Cultures. 



A pure culture is the growth of one kind of microorganism on a sterilized 



medium. 

 1. Molds. 



Molds in nature. Molds on hoi-se-dung, fruit, vegetables, preserves, milk 

 and dairy products, maple-sugar, ensilage, moist cotton-seed meal, 

 leather. 

 Permanent cultures In large culture flasks. Important molds: Penicillium 

 roqueforti and P. camemherti, help in cheese ripening. Penicillium ex- 

 pansum decays apples, P. italicum and P. digitatum decay oranges. 

 Aspergillus fumigatus, causing Aspergillosis of men and animals. 

 Oidium lactis, making butter rancid. 

 Microphotographs and clay models of various molds. Microscope with 

 Mucor and with Aspergillus (mounted in glycerin). 



