is complete for the distance specified above, invert the eyeball, squeeze and shake gently over some receptacle, such as a Stender dish, three-fourths filled with a 2½ or 5 per cent. solution of formaldehyde, and the hyaloid membrane containing the vitreous, its attachments, suspensory ligament to the lens capsule, and lens, will drop out intact, as when one empties the contents of an egg. (Fig. 6.) [Illustration: Fig. 5.--Picking up the choroid with the point of the scissors.] [Illustration: Fig. 6--A. Hyaloid, vitreous, and lens ready to drop out of the eyeball.] [Illustration: Fig. 7--Photograph of dissected hyaloid membrane (A), with pigmented indentations of the ciliary processes, the suspensory ligament (B), and the crystalline lens in its capsule (C). (Page 34.)] Many times a considerable amount of pigment from the second tunic will remain attached to the _processus zonuloe_. This pigment may be easily removed by scraping it off with the sharp edge of the scalpel or by brushing it off with a soft, wet tooth-brush. It is unwise to use alcohol as a preservative because it produces an almost immediate opaqueness and hardness which spoils the specimen for further study. This description may give the impression that the dissection is a lengthy one; however, it can be done by an expert in two or three minutes; by a beginner in five or six minutes. For purposes of demonstration or study the specimen should be placed in a small bottle or a vial containing a 5 per cent. solution of formaldehyde. It can then be examined with hand lens or microscope. (Fig. 7.) [1] Approved as an original article in _The Anatomical Record_, September, 1912. [2] This dissection, and several of the following, appeared in _The Optical Journal and Review_, beginning with the issue of January 16, 1913. THE CANAL OF PETIT 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. [Illustration: Fig. 8--A. Glass blowpipe. B. Petit’s canal.]