Organisms used in this laboratory. a Unicellular yeast fixed and stained with Congo red. b Multicellular yeast fixed and stained with methylene blue. a, b are provided in the snowflake yeast lab kit. c A rotifer, of the genus Philodina, when mixed with red unicellular yeast and blue multicellular yeast, will primarily eat red unicellular yeast (visible in the rotifers’ stomach through its transparent body).