The most satisfactory method of demonstrating to a student the points of difference between Ankylostoma duodenale and Necator americanus is by showing him the characteristics of the buccal capsule of each species. The difficulty, however, is with properly orienting the worm so that a direct view may be had of the mouthopening. Should a lateral view of the anterior extremity present, it is difficult to point out the anatomic differences.
On applying a cover-glass to a freshly passed worm in salt solution on a slide, it will be found easy to cause the worm to roll about its long axis by gently manipulating the surface of the superimposed cover-glass with an ordinary wooden toothpick. This manipulation can be readily carried on while the specimen is examined on the stage of the microscope with a 2/3 inch objective.
By proper adjustment of the diaphragm the proper amount of light can be