Fairleigh Dickinson University 1 article published in JoVE Biology Measuring the Effects of Bacteria on C. Elegans Behavior Using an Egg Retention Assay Mona Gardner1, Mary Rosell1, Edith M. Myers1 1Department of Biological and Allied Health Sciences, Fairleigh Dickinson University An egg-in-worm (EIW) assay is a useful method to quantify egg-laying behavior. Alterations in egg laying can be a behavioral response of the model organism Caenorhabditis elegans to potentially harmful environmental substances such as those produced by pathogenic bacteria.