BIRD’S-EYE VIEWS. 513 


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 oculo-motor divides into numerous branches, which 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 with food. The arteries 
ing the nutritious fluid, and the veins carry it away when 
the nourishment has been extracted for the repair of the 
destruction that constantly goes on in all living tissue, and 
When it has become loaded with carbon, and other effete or 
deleterious matter. 
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_ Presented to him. — To be concluded. 
NATURALIST, VOL. I. 65 
