218 PHYSIOLOGY. 



contraction serves to close the eye ; the other lying beneath, 

 are the fibres of the levator muscle, which serves to : aise the 

 Ud, or open the Syel These two muscles are well exhibited 

 in the following cut : 



Fig. 21. 



Muscles of the eyelids, the elevator passing back into the orbit ; the 

 sphincter, or orbicular muscle surrounding the eye. 



44. Around the margin of each lid, there is a delicate 

 elastic cartilage placed, which serves to preserve the shape 

 of the lid ; and into this, as is shown in the cut, the fibres 

 of the elevator muscle, are inserted. In contact and around 

 each cartilage, on its anterior surface, at the root of the eye- 

 lashes, is situated a row of little bags or follicles, which 

 secrete an oily fluid, to keep the parts soft and pliant, and 

 prevent the lids from sticking together. It is this matter 

 which we often find in the morning, collected on the margin 

 of the lids, or in the internal angle of the eye. 



45. Now, mark this difference ; the levator muscle, which 

 rises from the bottom of the orbit, is entirely under the con- 

 trol of the will ; the orbicular muscle is not. See the ad- 

 vantage of this. If we had always to issue a command of 

 the will to shut the eyes, before going to sleep, I imagine 

 there are a good many in this lazy world who would forget 

 to shut their eyes, and so go to sleep with them wide open. 

 To what dangers would they be exposed, and what injuries 

 might they not sustain in consequence ! But watch a 



