168 PHYLUM I. MYXOPHYCEAE 
these some will probably be found in process of fission. Larger 
br'ght-green cells filled with granular protoplasm will also be 
found; these are species of Protococcus belonging to the next 
phylum. 
(b) In midsummer look along the water-line of fresh-water 
lakes and ponds for soft, amber-colored, round masses from the 
s ze of a pea to that of a hickory-nut. By mounting 4 small 
sl'ce of one of these it will be seen under the microscope to be 
composed of myriads of filaments of Nostoc. Occasionally a 
filament may be seen with a heterocyst; its function is not 
known. 
(c) Secure a handful of the dark-green filamentous growth 
which is common on the wet sides of watering-troughs and 
place it in a dish of water. If an Oscillatoria, it will rapidly 
disperse itself, a few minutes being long enough to show quite 
a change i in position. Now mount a few filaments in water and 
examine under a high power. They will be seen to sway from 
side to side while moving quite rapidly across the field of the 
m*croscope. 
(d) In midsummer scrape off one of the small jelly-like 
masses of. Rivularia, so common on the submerged stems of 
water-plants; mount in water, crushing or cutting the mass so 
as to show the individual filaments. Each filament tapers 
from the center of the mass outward, and at its rest (inner) 
end there is generally a heterocyst. 
Some elementary studies of bacteria may be made very easily, 
but their profound study (Bacteriology) involves a technique 
which is unattainable by the beginner in Botany. The follow- 
ing may be attempted. 
(e) Boil a pinch of cut hay or any other similar vegetable 
substance for a few moments, and put into a glass of water; 
keep in a warm room for a couple of days, or until it be- 
comes turbid (from the abundance of bacteria); examine a 
minute drop with the highest powers of the microscope, for 
active bacteria. The bacterial growth originates from the 
spores which were not killed by the short boiling. The com- 
monest form thus obtained is Bacillus subtilis. 
(f) Put a bit of fresh meat into water, and study the bacteria 
which will appear in it. Spiral forms (especially Spirillum) 
may often be found in such a preparation. 
(g) Examine the juices of decaying fruits and vegetables. 
