44? Mrs. M. Griffiths's Observations on the 



veyed to my sight; but I soon recollected that my eyes were 

 shut, that the lids had not once been opened, and that my 

 face was directed to the ceiling; the squares, too, of the spec- 

 trum were placed diamond-wise and were of a different co- 

 lour from that of the window-sash so often seen by me. I 

 could not make the object return that morning, although I had 

 the room made dark and closed my eyes again. 



I inferred from this that during sleep the whole apparatus of 

 the eye is relaxed, and that there is a suspension of all effort, 

 consequently the fluids are not so abundantly present. While 

 in this state, the retina is taken by surprise, as it were, and 

 so becomes visible to the mind. If the lids had been open and 

 the senses on the alert before the shutters were opened, the small 

 portion of light always perceptible in a room not particularly 

 closed against it, would be sufficient to stimulate the nerves 

 and keep the retina in a state of tension ready for use. 



Subsequent and repeated experiments by myself and others 

 have not only reduced this fact to a certainty, but they have 

 elicited others, all confirming the opinion that the retina 

 is not the seat of vision. In several instances I discovered 

 that the retina had the power to contract and expand, for the 

 squares of the meshes were at times wider apart than usual ; 

 and when thus expanded the lines or intersections were thinner 

 and paler. The meshes were generally the fifth of an inch 

 asunder, varying with the health of the body, the quantity of 

 light thrown on the closed lids, and the period of the day when 

 the closed eye was exposed to the glare of light. 



When the eyes are covered in a dark room after dinner, 

 and we lose ourselves for a few moments in sleep, and the 

 shutters are suddenly opened, before we open our eyes or rub 

 them., then a different thing takes place. We shall not see 

 the intersections or threads of the retina, but the squares or 

 interstices between them, which have the appearance, first of 

 a dark, and then light colour. In the centre of each square, 

 while the colour is light yellow, a bright star will be often seen, 

 about the size of the head of a large pin : as soon as the light 

 yellow colour changes to black, the star disappears; but when 

 the light colour returns, the star is again seen, or rather the 

 place where the star stood is now occupied by a faint light. 

 When the stars are first seen, they twinkle or scintillate ; and 

 finally, if the glare of light has been strong, on covering the 

 eyes suddenly with the hands, the whole vanishes in wavy lines, 

 which are certainly the undulations of the meshes of the re- 

 tina, for we can easily infer that the retina can be raised or 

 depressed. Throughout the whole appearance the place of 

 the pupil is open and distinct, sometimes contracting and 



