INTRODUCTION
      Sometimes scientists want to prepare slides of living protists in such a way that certain
structures and/or behaviors can be observed. For example, a scientist may wish to know how a
certain protist is swimming or what it’s feeding on. Such information can only be collected by
observing living, moving protists. In the following lab we will be
           1. preparing and viewing protests using the hanging-drop technique,
           2. making detailed observations of known algae and protozoa,
           3. locating and observing unknown protists cultured in an infusion.
      Obtain a clean concave slide and cover slip. Prepare a hanging-drop slide of each
specimen using the technique shown in the diagram below. First observe the protists under
low power (use high power if it appears small) and collect the information requested in the
Data Sheet. Be sure to show the protist to the instructor whenever instructed to do so in the
data sheet.

When done with each slide, the slide and coverslip should be cleaned and reused following the
steps listed below:
      a. Slides --> Remove petroleum jelly using toilet paper, rinse in soapy water, dry with
                 paper towels, and reuse. Return slides to original source at end of class period.
      b. Coverslips --> Remove petroleum jelly using toilet paper, rinse in soapy water, dry
                with toilet paper, and reuse. Throw away at end of class period.

PROCEDURE
Part A: Observations of Known Protists
      Locate the tubes of known algae and protozoa located around the lab. Each tube will have
its own medicine droppers for removing a drop of culture and placing it on the slide. (DO NOT
move medicine droppers from one area to another!) Make each slide, fill in the data requested
on the Data Sheet, clean the slide, and repeat. 3 to 4 specimens should be completed each
day of this lab. The conditions for handling each tube varies depending on the organism present.
Follow these instructions closely:
      a. Algaes --> Oedogonium, Spirogyra, & Oscilatoria || SHAKE WELL before removing |
                      DO NOT remove large clumps.
      b. Algaes --> Euglena, Chlamydomonas, & Volvox || DO NOT shake | specimens usually                            located equally throughout container.
      c. Protozoa --> Paramecium & Algae || DO NOT shake or create current with dropper |                                        specimens will settle to bottom of container if undisturbed. (Squeeze dropper
                      before nearing bottom of container)

Part B: Observations of Unknown Protists
      Locate the container(s) of unknown protists located around the lab. Inside these containers
are infusions made of some plant matter (usually hay or straw) and some untreated water. Each container will have its own medicine droppers and/or pipettes for removing a drop of culture and
placing it on the slide. (DO NOT move the medicine droppers or pipettes from one container to
another!) Make each slide, fill in the data requested on the Data Sheet, clean the slide, and
repeat. Be sure to remove specimens from different areas in the culture container (ex -> top,
bottom, middle, near vegetation, clear areas, etc). 3 to 4 specimens should be completed each
day of this lab.
      Upon making each slide select one specimen to observe. If it moves try to follow it by
moving the slide, and observe how it moves. If it’s stationary try to observe it under high power
and observe internal structures. Complete the data sheet using the information listed at the top
of the Data Sheet.
                    (NOTE -> If you see the same protist twice in the same location in the
                     specimen container do not draw it twice, but if you see it again from
                     a different location in the specimen container then you should draw
                    it both times.)

QUESTIONS
1. Algae are autotrophic.
      a. Define autotrophic.
      b. How are the algae obtaining energy in both the culture tubes and in the infusion?
2. Protozoa are heterotrophic.
      a. Define heterotrophic.
      b. How are the protozoa obtaining energy in the infusion?
3. List one characteristic common to the three algaes Oedogonium, Spirogyra, and Oscilatoria.
4. List one characteristic common to the two algaes Euglena and Chlamydomonas.
5. List one characteristic that makes Volvox different from all the other algaes viewed in this lab.
6. A common infusion is a hay infusion. Such a culture contains only untreated water and hay.
      a. From where do the protists come from?
      b. Can a hay infusion sustain itself for a long period of time (1 year or more)? Explain.
7. In most hay infusions there will be protists present in a wide variety of sizes. What might the
      larger protists be feeding on?
EXTRA CREDIT:
8. Smell the infusion. Over time all infusions begin to create an offensive odor. Neither the
      algae nor the protozoa are producing this odor. What other microorganism might be
      producing this odor?