The effect of a depressant on the Bpm of Lumbriculus variegatus in comparison to the effect of plain water INTRODUCTION: The Lumbriculus verigatus is a very good specimen to use when trying to view a closed circulatory system. Due to its translucent epidermis you are able to easily view the circulation of blood throughout the body of the worm. In this experiment we used worms that were placed in plain water and in a depressant solution, in order to observer the effect of the depressant on the heart rate of the worm. PROCEDURE: Place worms in appropriately marked containers. Transfer five worms from depressant and plain water trays in to their respectable containers by pipette. Select on worm from the depressant water and place into well slide with a cover slip on top and view with microscope. (Less water means less movement) Monitor and record the pulse rate of the worm Repeat steps 3-4 using five total worms. Repeat steps 3-5 using worms from plain water container. CONCLUSION: At the end of this experiment we found the depressant actually worked well on the lumbriculus variegatus there was a difference of three beats per minute. But we believe if given sufficient enough time to do more tests on more worms then the results will be stronger. If there was a test with 20 worms for each group then there would be a large difference in the averages of the pulse rates. RESOURCES: In class data www.eeob.iastate.edu/faculty/drewesc.htdoc HYPOTHESIS: If the worm was in the regular water then it pulse rate will be faster than that od a worm in depressant water. DATA: VARIABLES: Independent variable: The independent variable for this experiment is a depressant given by the teacher. Dependant variable: the dependant variable is the pulse rate of the lumbriculus variegatus. Control group: the control group is the group placed in the regular water. Controlled variables: temperature, lab is stress free for the worm, all of the worms should be from the same area, and chemicals use on the worm should be of a natural source or one that the worm can handle. MATERIALS: Light-compound microscope Well Slide Pipette Cover slip Stop watch Altered and plain water California Black worms Permanent marker Four small plastic cups