1798 Journal of Applied Microscopy 



LABORATORY OUTLINES. 



For the Elementary Study of Plant Structures and Functions from 

 the Standpoint of Evolution. 



VIII. Bacteria. Class, Schizomycetes. Order, Bacteriales. 

 There are three families of bacteria : 



CoccacecB, Spherical Bacteria, containing the genus Micrococcus and 



others. 



Bacillacece, Rod Bacteria, containing the genus Bacillus and others. 



Spirillacea, Spiral Bacteria, containing the genus Spirillum and others. 



To obtain Bacilli, make a hay infusion by boiling ordinary dry hay for 15 



minutes. Keep in a sterilized covered dish for several days. Also boil some 



beans, and after exposing the broth to the air until cool, cover and set aside for 



two or three days. Species of Spirillum may be obtained from sewer water, or 



by letting water plants decay in a jar of water. Micrococci are common in the 



air, and may be obtained on boiled potatoes, gelatin, moist bread, etc., by letting 



these culture media remain exposed for a short time and then covering them to 



keep in the moisture. The bacteria will soon begin to appear in yellow, pink, 



purple, or red patches. 



1. Mount some of the hay infusion and examine under high power. Notice 

 the minute free-swimming hay Bacillus, and draw several individuals. Draw 

 several still hanging together in a filament after division. Describe the shape, 

 color, and movement. Distinguish between the true locomotion of the Bacillus 

 and the Brownian movement of the foreign particles present in the mount. 



2. Draw two individuals with spores. The movement is produced by means 

 of fiagella or cilia. 



3. Mount some of the bean broth and notice the putrid odor. Study the 

 Bacillus present. Estimate the number of bacteria present in the field of the 

 microscope. Counting the number across the diameter of the field and squaring 

 will give approximate results. 



4. Suppose you had one bacterium to begin with, and that it and its de- 

 scendants divided once every hour, how many bacteria would there be at the end 

 of each hour for 48 hours ? 



5. Mount some material containing Micrococcus. Draw several individuals 

 and describe. 



6. Mount and study some bacteria in the zoogloea stage (bacteria in gelatinous 

 masses). Draw and describe. 



7. Mount some water containing Spirillum. Study the peculiar movement. 

 Draw several individuals and describe. 



8. Mount some hay Bacilli and some Paramoecia together, and compare 

 them as to size. The Bacillus and the Paramoecium are both single cells. 

 About how much greater in volume is the ParamcEcium than the Bacillus ? In 

 order to get fairly accurate results, find how many times wider, thicker, and 

 longer the one is than the other. How near would the comparison hold with 

 that of a mouse and an elephant ? 



