The canal of Petit is a “triangular space around the circumference of the lens.” That it can be “inflated through a fine blowpipe inserted through the suspensory ligament,” is the usual direction given. However, the ordinary “fine blowpipe” is much too large and too dull to be inserted through the suspensory ligament. Take a long medicine-dropper (5 or 10 cents at a drug store), or a pipette, and heat it until it is red hot over an alcohol lamp or a Bunsen burner; hold one end with one hand and the other end with a pair of tweezers. As the glass becomes white hot pull the tube apart. This will leave the places of separation pointed and sharp-edged. Use the larger of the two pieces. Sometimes the point or tapering end of the tube is too long and the bore too small. All that is necessary is to first mark off with a file the length to be broken off, and then that length may be snapped off, leaving a sharp-edged, tapering point.

After having completed the first dissection (the hyaloid, contents and attachments), and the specimen has been in the formaldehyde solution for ten days or two weeks, it will have become hard and tough enough to stand a considerable amount of rough handling. If the specimen has been kept in a large receptacle, such, for instance, as a jar, remove it with a spoon; if in a small jar or vial, empty out the fluid, then slide the specimen out on whatever has been prepared to receive it. Turn it so that the lens will be uppermost. Find the suspensory ligament in the Zone of Zinn. Insert the pointed end of the glass tube, close to the lens, and blow gently until the canal shows its sacculated construction by filling with air, giving the appearance of a lot of little bubbles surrounding the periphery of the lens. (Fig. 8.) It may be necessary to move the blowpipe in and out in order to find the canal, all the while blowing steadily through the tube.