[Illustration: Fig. 29--Taking out the lens and “core” of the vitreous.] [Illustration: Fig. 30--Showing how to squeeze out the remaining part of the vitreous (A) from the choroid. (Page 71.)] This specimen will show the vena vorticosa, the ciliary nerves, and their way of ramifying, and the long ciliary arteries, which run opposite each other and which may be recognized by their rather colorless, tubular appearance. The evacuated choroid makes an excellent specimen and one easily examined. Place it in a 3 per cent. solution of formaldehyde, and then examine with a skiascope, an ophthalmoscope, or by “oblique illumination.” This dissection is wholly original, and may be done in about five minutes. The old technique for doing it required at least an hour of time with the possibility of procuring one perfect specimen in every six or seven. The technique as given here will make it possible to do the work in not longer than five or six minutes for the beginner, and about four minutes for the expert. THE RETINA Isolating the retina from the other tissues requires considerable patience and dexterity. When the retina has been removed and placed in a special receptacle, it will be found that the specimen is well worth the little amount of time spent in making it. Previous techniques, even the writer’s own, sometimes took nearly two hours to do, and rarely was the retina isolated without puncturing or tearing it; perfect specimens were almost impossible. The following method will assure one of success in nearly every instance. Failures are almost impossible. Punctures, perforations, tears, etc., are rare. The beginner should isolate the retina in about six to seven minutes; the expert in about four and a half to five minutes. Select an eye with a long optic nerve, and prepare it for this dissection by placing it in a 10 per cent. solution of formaldehyde for about ten to fourteen days, but no longer. If it is left in the hardening fluid longer than that length of time, it will interfere with the easy removal of the vitreous. [Illustration: Fig. 31--Cutting through the iris. (Page 77.)] [Illustration: Fig. 32--Showing how to cut around the ciliary ring. (Page 77.)] The first part of this dissection is the same as the beginning of the dissection for the isolation of the choroid. Remove all the outside tissues first, and then the cornea, and about 10 mm. of the sclerotic, as described in the preceding dissection. (See Figs. 22, 23, 24, and 25.) That will lay bare the iris and a few millimetres of the choroid. [Illustration: Fig. 33--Lens, iris, and part of vitreous removed. (Page 78.)]