THE TEMPERAMENTS. 211 



diameter. When this funnel is supported on a wire-stand, so as to bring the gold- 

 beater's skin into a horizontal position, and some fine sand is placed on it, the vibrations 

 produced by the air may be seen, by beating on a sheet of tin, or other strongly vibrat- 

 ing body, at the larger extremity. Any tinsmith will give the shape for the paste- 

 board. 



The structure of the eye can be admirably shown. Direct attention to the puncta 

 lachrymalia ; to the appearance of the pupil, contracting and dilating as more or less 

 light is directed on the eye ; to the correspondence of the motions of the two eyes 5 the 

 color of the iris, &c. The muscles of the eyeball can be beautifully seen in the sheep, 

 but they require a good deal of dissection. The globe of the eye may be easily shown, 

 however. Get a bullock's or sleep's eye, clear off the fat, &c., and observe the optic 

 nerve entering it posteriorly. Take hold of the optic nerve, introduce a pair of sharp 

 scissors through its coats, rather more posteriorly than the middle of the globe, and cut 

 the coats round transversely. The exterior sclerotic coat, the pulpy retina (often curled 

 up) interiorly, and the choroid coat between these, will then be seen. Some of the 

 vitreous humor will probably escape in making the section, and both it and the lens, 

 lying behind the pupil, will be seen when the posterior section of the eye is removed. 

 A number of lines on the choroid coat, radiating from the circumference of the lens, 

 and called ciliary processes, may also be seen. The aqueous humor may be seen to 

 escape when the eye is made tense (when entire), and the cornea is punctured. The 

 iris may be examined when the humors are removed. A similar section of a cod's eye 

 should be made to show the globular lens. The eye of a fowl may also be examined, 

 and its bony sclerotic, third eyelid, &c., observed. 



Such a section as has been mentioned should, of course, always be made, but the 

 anatomy of the eye is made much more simple by having a horizontal section model of 

 it. In this its coats, humors, &c., are all seen, and their relations may be comprehended 

 with the utmost ease by young students. 



To show the inverted image on the retina, the eye of a white rabbit answers well. 

 It is seen best by candle light, and when two or three lights are moved before the eye. 

 All the muscles and fat must first, of course, be removed posteriorly. 



A prism, to show the decomposition of light, and a small camera obscura, should be 

 exhibited. 



For figures to illustrate this chapter, see Lizars' Colored Plates, pages 75, 76 ; Roget's 

 Bridgewater Treatise, vol. ii., pages 384, 400, 401, 425, 464, 467.] 



CHAPTER XIV. 



THE TEMPERAMENTS. 



THERE are four of these : 1st, The lymphatic, in which there is 

 easily seen a full, soft, and rounded form, and languid action. 



2d, The sanguine, in which there is a florid complexion, ex- 

 panded chest, and general vivacity of disposition, showing the pre- 

 ponderance of the vascular system, known generally by the term 

 of plethoric or full habit, the circulation of the blood being very 

 full and strong. 



