bird's-eye views. 9 



besides those already described, and the ball itself. There 

 are nerves, arteries and veins. Of the first named, the 

 optic, or sight-nerve, is by far the largest, and is in fact the 

 only one that can be discerned without more trouble than 

 most persons would be willing to take to see it, and more 

 skilful dissection than most can make. It is described further 

 on, as it can be more conveniently studied in connection with 

 the ball itself. Other nerves go to the muscles of the eye. 

 The ocido-motor divides into numerous branches, Avhich are 

 distributed to the inferior oblique, and all the recti except 

 the external. The latter claims a nerve of its own (the 

 abducens), and so, also, does the superior oblique, to which 

 the patheticus is exclusively distributed. These nerves all 

 come directly from the brain. We do not know why they 

 are so unequally distributed. There are some more nerves 

 in the socket which, however, do not particularly concern 

 the eye, and therefore need not concern us. There is little 

 to be said of the blood-vessels : they ramify everywhere, sup- 

 plying all the structures of the eye Avith food. The arteries 

 bring the nutritious fluid, and the veins carry it awa}^ when 

 the nourishment has been extracted for the repair of the 

 destruction that constantly goes on in all living tissue, and 

 when it has l^ecome loaded with carbon, and other efiete or 

 deleterious matter. 



So much for the surroundings of a bird's eye, — the setting 

 of the precious stone : now Ave are prepared to look inside. 

 An eye is a perfect microcosm, in Avhich Ave find almost 

 every kind of tissue that enters into the composition of the 

 rest of the body. If the reader's interest has been aAvakeued, 

 as Ave hope it has, by Avhat has gone before, Ave can, Avith 

 confidence, invite him to look deeper into a laird's eye, and 

 give him assurance that a far more beautiful "VicAv" Avill be 

 presented to him. — To he concluded. 



(2) 



