54 



MICROBIOLOGY 



In addition to the microscope, slides, cover-glasses and 

 cover-glass forceps are necessary. For examining living 



Fig. 14. Slides for 

 studying living bacteria 

 Fig. 13. Varieties of forceps with cover-glasses in 



used for handling cover-glasses. place. 



bacteria it is necessary to have a culture cell, or better, an 

 ordinary glass slide on which is cemented a glass ring about 

 1.2 cm. in diameter and 1 to 3 mm.* in thickness. To stain 



Fig. 15. 







10 CENTIMETER RULE 



The upper edge is in millimeters, the lower in centimeters, and half centimeters. 



THE METRIC SYSTEM 



UNITS. The tnost commonly used diinsions and multiples. 



Centimeter (cm.), 0.01 Metei ; Millimeter (mm.), 0.001 Meter: Micron 



(iu.) 0.001 Millimeter; the Micron is the unit in Micrometry. 

 Kilometer, 1000 Meters ; used in measuring roads and other long dis- 

 tances. 



Milligram (mg.), 0.001 Gram. 



Kilogram, 1000 Grams, used for ordinary masses, like groceries, etc. 

 Cubic Centimeter (cc. ), 0.001 Liter. This is more common than the 



correct form, Milliliter. 



Divisions of the Units are indicated by the Latin prefixes: deci, 0.1; centi, 0.01: 

 milli, 0.001; micro, one millionth (0.000001) of any unit. 



Multiples are designated by the Greek prefixes : deka, 10 times ; hecto, 100 times : 

 kilo, 1000 times; myria, 10,000 times; mega, one million (1,000,000) times any unit. 



THE METER FOR 

 LENGTH. . 



THE GUAM FOR ( 

 WEIGHT. . . I 



THE LITER FOR f 

 CAPACITY. . \ 



