Be supplied with two knitting-needles. Take one, lubricate its full length with a little vaseline, lard, oil, or any other lubricant. Insert the needle into the punctum of the lower lid, and push it downward and forward, aiming to come out in the nose a short distance from its end. At first it may be a little difficult to get the needle started; if so, just wiggle the needle, pushing it at the same time as directed, until the nasal duct is found. Do not remove the needle. To insert the other needle into the punctum of the upper lid is rather difficult; for that reason the punctum of the lower lid was chosen, first. Grease the needle, as was done to the first one, and, with a little patience and careful manipulation, the canal opening and its course will soon be found. The needle may then be pushed through until it meets the first one. (Fig. 45.) From the puncta lacrimalia to the place of meeting of the two needles, marks the course of the two canaliculi and their junction before they merge and form the nasal duct. Leave the needles where they are, and begin cutting away the skin. The needles will then mark the course of each canal and the duct very plainly. With the small scissors the canals and the duct may be loosened from the surrounding tissues. Or, the scalpel may be used to lay open the canals, cutting along over the top of the needles. (Fig. 46.) The cilia, palpebræ, palpebral conjunctiva, ocular conjunctiva, and other superficial ocular accessories may be examined without dissection. MEIBOMIAN GLANDS AND DUCTS An examination of the eyelids will show the openings of the ducts of the meibomian glands a short distance back of the cilia. Very fine pins or needles that have been greased may be easily inserted for a short distance into the ducts, and then a dissection made along the course of the duct as outlined by the presence of the inserted pins or needles. Another way to see the glands is to slice through the ducts, with the scalpel or safety-razor blade, the entire width of either eyelid. This will separate the glands into two parts and show their length, breadth and structure. ENUCLEATION OF THE ORBITAL CONTENTS The eyes one procures from a butcher or a slaughter house will always have the extrinsic tissues so badly cut and torn that identification of the various parts and their relations is impossible. Therefore, it is best to supply one’s self with the head of an animal, such as a sheep or a calf, and dissect an eye with all its extrinsic tissues intact. For this dissection, a hammer and a chisel are necessary in addition to the tools needed for doing the previous dissections. [Illustration: Fig. 47--Showing method of making the initial cuts in the skin. (Page 97.)] [Illustration: Fig. 48--Part of calf’s head, showing the first cut to be made in the bones of the orbit. (Page 102.)] [Illustration: Fig. 49--Showing all the cuts to be made through the bones of the orbit. (Page 102.)]