MORPHOLOGY Fe pl : 57 
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EXERCISE XV 
THE MORPHOLOGY OF BACTERIUM, BACILLUS, AND 
SPIRILLUM 
85. The organisms which are to be studied in this exer- 
cise exhibit in addition to the rod-shaped bodies (bacterium 
and’ bacillus) the essential morphological variations of these 
genera, viz. number of flagella and spores. The staining of 
the organs of locomotion (flagella) and the spores will be taken 
up in another exercise. 
86. Work for this exercise. Carefully examine and study 
the cultures made in Exercise XIV, following the directions 
given for the examination of cultures and preparations in that 
exercise. 
Measure carefully with the filar micrometer the length and 
thickness of 5 individual bacteria in one of the stained prepa- 
rations. Record the measurements in microns (written 4). 
Make a drawing, magnified 1000 diameters, of a few indi- 
viduals from each of the stained preparations from the agar . 
cultures. . 
State fully in the notes the generic characters of the genera 
Streptococcus, Micrococcus, Sarcina, Bacillus, Bacterium, and 
Spirillum. 
Prepare water suspensions for staining flagella (§ 91). 
87. Making drawings of bacteria with a definite magnifica- 
tion. In measuring the bacteria we obtain the dimensions in 
microns or in units of ya55 of a millimeter. In making a 
drawing, therefore, showing them magnified 1ooo diameters, 
it is simply necessary to represent each micron by a milli- 
meter. Thus, if the organism is 2.5 4 in length and 1 wbroad, and 
the drawing is to represent the organism magnified 500 diame- 
ters, then each micron should be represented by 0.5 mm. For 
this purpose a metric rule and a pair of dividers are necessary. 
