It is often desirable that a mid-gut showing oocysts be preserved for demonstration purposes or for record. The method herein described seems to have certain advantages over those usually recommended in saving considerable time during fixation, staining and mounting of the specimen, also in permitting pigment within oocysts being seen on any part of the mid-gut. The stain used (toluidine blue) is not taken up to any great extent by the nuclei of the gut cells, but appears to have some degree of selective action on the younger oocysts.