Feeding of Nippostrongylus brasiliensis in oxygen and serum

ornatum is 22 for females and 21 for males, and the sex determining mechanism is XX: XO. We thank Dr. W. J. Gladney for sending us specimens of A. inornatum from which our laboratory colony originated. Thanks are also extended to Dr. J. Mathews Pound for help with the figure and to him and Cheryl Morris for editorial and clerical assistance. This research was supported in part by Grant AI-09556 from the National Institute of Allergy and Infectious Diseases (NIH) and Contract N-00014-80-C-0546 from the Office of Naval Research.