TYPES OF CRYPTOGAMS; THALLOPHYTES 239 
266. Microscopic Examination. — Examine some of the cultures. 
Place a particle of the growth on a slide, dilute it with a drop of 
clear water, and place a cover-glass over it. Examine with the 
highest obtainable power of the microscope, at least } in. objective. 
Note the forms and movements, also the sizes if practicable, of any 
bacteria that are found. 
THE STUDY OF OSCILLATORIA! 
267. Occurrence. — Oscillatoria may occur floating in stagnant 
water or on damp soil in ditches, roadsides, dooryards, paths, or 
pots in greenhouses. Other nearly related plants occur on surfaces 
of ponds sometimes covering considerable areas or adhering in small 
spheres to submerged vegetation. Algz of this class are particu- 
larly noxious in water supplies, as they partake of the nature of 
bacteria, to which they are related. 
268. Examination with the Microscope. — After washing a particle 
of Oscillatoria material in a drop of water to remove as much of the 
earth as possible, place it in a clean drop of water, pull to shreds 
with needles, cover, and examine under a power of 200 or more 
diameters. 
Note the color and compare it with chlorophyll green. 
The filament is not one plant, but each of the cells which com- 
pose it is one plant. They are packed together in the filament like 
coins and sometimes may be found separating singly. The usual 
mode of reproduction is by the separation of a number of adhering 
cells as a short filament from one end of a longer one, and this 
increases in length by the dividing of its individual cells. 
269. Movement.— At ordinary temperatures, favorable to growth, 
movement may be observed in the filaments. - Describe the move- 
ment. What has it to do with the name of the.plant? 
1 A genus of the class Schizophycez. 
